specification_pressure vessel

0 ASA 23.09.02 AVV 24.09.02 AD 27.09.02 ISSUED AS STANDARD SPECIFICATION

Rev. Name Date Name Date Name Date Remark, kind of revision

Prepared, revised Checked Approved

Standard Specification for

Pressure Vessels

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LI-0-FMT-0001

Issue: Rev. 00 , 25.08.2000

Standard Specification

For Pressure Vessels

Table of Contents

Section

1 SCOPE................................................................................................................................................. 5

1.1 Definitions............................................................................................................................................. 5

1.2 Scope of Supply.................................................................................................................................... 5

2 STANDARDS AND CODES..................................................................................................................5

2.1 Local Regulations.................................................................................................................................. 5

2.2 Standards............................................................................................................................................. 5

2.3 Conflicts................................................................................................................................................ 5

3 PROPOSAL INSTRUCTIONS...............................................................................................................6

4 DESIGN................................................................................................................................................ 6

4.1 General................................................................................................................................................. 6

4.2 Process Design..................................................................................................................................... 6

4.3 Guarantees........................................................................................................................................... 6

4.4 Code Requirements.............................................................................................................................. 6

4.5 VENDOR’s Design Basis....................................................................................................................... 7

4.6 Document submission........................................................................................................................... 7

4.7 Mechanical Design................................................................................................................................ 8

4.7.1 Design Pressure................................................................................................................................... 8

4.7.2 Design Temperature.............................................................................................................................. 8

4.7.3 Corrosion Allowance............................................................................................................................. 8

4.7.4 Minimum Thickness.............................................................................................................................. 8

4.7.5 Heads, Transitions and Discontinuities..................................................................................................9

4.7.6 Calculation............................................................................................................................................ 9

4.7.7 Loading............................................................................................................................................... 10

4.7.8 Internal Loads..................................................................................................................................... 12

5 MATERIALS....................................................................................................................................... 13

5.1 Material Selection................................................................................................................................ 13

5.2 Material Substitution............................................................................................................................ 13

5.3 Material Identification.......................................................................................................................... 13

5.4 Alloy Lining......................................................................................................................................... 14

6 MANUFACTURE................................................................................................................................ 14

6.1 General............................................................................................................................................... 14

6.2 Additional Requirements for Fabrication of Stainless Steel...................................................................15

6.2.1 General............................................................................................................................................... 15

6.2.2 Materials Segregation.......................................................................................................................... 15

6.2.3 Fabrication Conditions......................................................................................................................... 15

6.2.4 Heat Treatment................................................................................................................................... 15

6.3 Reference Work Line........................................................................................................................... 15


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6.4 Location of Weld Seams...................................................................................................................... 15

6.5 Heads................................................................................................................................................. 16

6.6 Nozzles............................................................................................................................................... 16

6.6.1 General............................................................................................................................................... 16

6.6.2 Nozzle Attachment.............................................................................................................................. 17

6.7 Reinforcement of Openings.................................................................................................................17

6.7.1 Nozzle Size......................................................................................................................................... 17

6.7.2 Davits................................................................................................................................................. 17

6.7.3 Flange Faces...................................................................................................................................... 17

6.8 Gaskets.............................................................................................................................................. 17

6.9 Bolting................................................................................................................................................. 18

6.10 Supports............................................................................................................................................. 18

6.10.1 Skirts.................................................................................................................................................. 18

6.10.2 Templates........................................................................................................................................... 18

6.10.3 Leg Supports....................................................................................................................................... 19

6.10.4 Horizontal Vessels.............................................................................................................................. 19

6.11 Internals.............................................................................................................................................. 19

6.11.1 General............................................................................................................................................... 19

6.11.2 Internal Piping..................................................................................................................................... 19

6.11.3 VENDOR’ Scope................................................................................................................................. 19

6.11.4 Provisions for Internal Lining................................................................................................................20

6.12 External Attachments.......................................................................................................................... 20

6.13 Vessel Accessories............................................................................................................................. 20

6.13.1 Name Plate......................................................................................................................................... 21

6.13.2 Lifting Lugs......................................................................................................................................... 21

6.13.3 Earthing.............................................................................................................................................. 21

6.14 Welding............................................................................................................................................... 21

6.15 Heat Treatment................................................................................................................................... 21

6.15.1 Code Requirements............................................................................................................................ 21

6.15.2 Local Heat Treatment.......................................................................................................................... 22

6.15.3 Treatment before and after PWHT.......................................................................................................22

6.16 Tolerances.......................................................................................................................................... 22

7 INSPECTION AND TESTING.............................................................................................................22

7.1 General............................................................................................................................................... 22

7.1.1 PURCHASER’s Inspection.................................................................................................................. 22

7.1.2 Test Records...................................................................................................................................... 23

7.1.3 Additional Test and Inspections...........................................................................................................23

7.1.4 Notice of Inspection and Examination..................................................................................................23

7.1.5 Pre-Inspection Meeting........................................................................................................................ 24

7.2 Air Testing of Reinforcing Plates..........................................................................................................24


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7.3 Hydrostatic Tests................................................................................................................................ 24

7.3.1 General............................................................................................................................................... 24

7.3.2 Pneumatic Test................................................................................................................................... 24

7.3.3 Bolts and Gaskets............................................................................................................................... 24

7.3.4 Testing Water Conditions.................................................................................................................... 24

8 PREPARATION FOR SHIPMENT.......................................................................................................25

8.1 Preservation........................................................................................................................................ 25

8.2 Closures............................................................................................................................................. 25

8.3 Loose Items........................................................................................................................................ 25

8.4 Match-Marking.................................................................................................................................... 25

8.5 Loading and Anchoring........................................................................................................................ 25

8.6 Painting............................................................................................................................................... 25

8.7 Marking............................................................................................................................................... 26

9 DATA FOLDER................................................................................................................................... 26


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1 SCOPE

This specification together with other listed Codes, Standards, Specifications and Mechanical Data Sheets, defines the minimum technical requirements for the mechanical design, fabrication, inspection, testing, transportation packing and supply of unfired pressure vessels.

1.1 Definitions

For the purposes of this specification the following definitions shall be used:

“PURCHASER” means the prime contractor for the EPC

“VENDOR“ means the person, firm or company who sells or furnishes the materials

1.2 Scope of Supply

All vessels shall be supplied complete as shown on the PURCHASER’s drawings and as specified herein including all necessary blind flanges, studs, nuts, gaskets, clips, davits and internals piping.

As a minimum all parts welded to pressure parts shall be within VENDOR’s scope unless excluded specifically from the scope.

2 STANDARDS AND CODES

2.1 Local Regulations

National Laws and regulations together with any local by-laws for the country or state wherever the vessels are to be used must be complied with by the fabricator. It shall be vendor’s responsibility to take approval for design, material of construction, fabrication, inspection and testing from statutory authorities including and not limited to IBR, Chief controller of explosive, etc.

2.2 Standards

The latest issues of the following codes/ standards are referenced by this specification and shall be used as minimum requirements:

ASME Sec II Materials

ASME Sec V Non-destructive Examination

ASME Sec VIII Div. 1 – Rules for Construction of Pressure Vessels

ASME Sec VIII Div. 2 – Alternative Rules for Construction of Pressure Vessels

ASME Sec IX Welding and Brazing Qualification

WRCB 107 Welding Research Council Bulletin 107: Local Stresses in Spherical and Cylindrical Shells due to External Loading

IBR Indian Boilers Regulation (where ever applicable)

SMPV Rules The Static and Mobile Pressure Vessels Rules (where ever applicable)

BS-5500 Appendix G Stresses in large horizontal cylindrical pressure vessels on two-saddled supports by L.P. Zick

2.3 Conflicts

If conflict occurs between PURCHASER supplied documents, it shall be informed to the PURCHASER and shall be clarified by PURCHASER.


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3 PROPOSAL INSTRUCTIONS

Each Vendor shall submit a base proposal for equipment complying strictly with this specification and the reference documents listed in Paragraph 2.2. Conflicting requirements in these documents shall be referred to PURCHASER for resolution prior to submission of the proposals.

Vendors may submit alternative proposals that deviate from PURCHASER’s requirements if significant savings can be demonstrated. Such proposals will receive full consideration, provided each deviation is fully described and the corresponding documents are provided.

The PURCHASER reserves the right to accept any alternative proposal without further consideration of the Vendor. An alternative design shall not be used unless it is approved in writing by the PURCHASER.

No subletting of any fabrication or welding will be permitted after the award of contract, unless prior approval has been taken from PURCHASER.

4 DESIGN

4.1 General

Mechanical Data Sheet which includes material specifications, principal dimensions, general requirements codes etc. will be furnished by PURCHASER.

4.2 Process Design

Where process design by the VENDOR is required it shall be so indicated on the vessel data sheet.

The VENDOR shall size the vessel when so required within limitations stated on the vessel data sheet. It will be the VENDOR’s responsibility to design all internals.

Vessel size and internal design shall permit internal access to all welds for inspection and non-destructive examination proposed during fabrication and for in-service inspection/ maintenance.

4.3 Guarantees

The Vendor shall guarantee the equipment and their components against defect in design, materials and workmanship. Approval by PURCHASER of design calculations and detail fabrication drawing will not anyway absolve the VENDOR from his responsibilities to supply equipment in accordance with order specifications.

Where process design of the equipment is provided by the VENDOR, the performance of the equipment shall be guaranteed to satisfy the specified process requirements.

4.4 Code Requirements

Except as otherwise shown or specified, all pressure vessels complying with this specification shall as a minimum meet the requirements of ASME Section VIII - Div. 1 or ASME Section VIII - Div. 2, where ever applicable.

When ASME Section VIII - Div. 1 or Div.2 is specified on the PURCHASER´s Mechanical Data Sheets and/or drawings, the design, materials, fabrication, inspection and testing shall meet the requirements of the latest edition and addenda of the Code.

Vessels intended for vacuum service greater than 500 Pa (50 mm water gauge), shall be designed and constructed according to ASME Section VIII - Div. 1.

When a pressure vessel designed according to ASME Section VIII, Div. 1 is specified to be in cyclic service, the design criteria and rules of ASME Section VIII, Div. 2 shall be used to perform an analysis, except that when establishing the need for analysis, the allowable stress limits of ASME VIII, Div.1 shall be used.


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4.5 VENDOR’s Design Basis

Vessel data sheets, sketches and any standard details supplied by the PURCHASER are intended to convey minimum design requirements and shall not be used by the VENDOR for fabrication purposes.

Thickness of components pre-dimensioned by the PURCHASER and specified in the drawing/data sheet shall be regarded as minimum values, after forming, including corrosion allowance. Should the VENDOR's calculations result in greater thickness, the PURCHASER shall be informed without delay.

4.6 Document submission

Vendor shall submit drawings and documents to PURCHASER as per following list but not limited to for approval.

Code calculations including nozzle reinforcement calculations, local stress analysis for nozzles and vessel clips due to external loads, thermal stress analysis whenever applicable or if specifically asked for, structural calculations for supports, internal lifting lugs etc.,

Complete shop fabrication drawings. Following details shall also be furnished as a minimum:

1. Erection, Empty, operating and hydrotest weights.

2. Heat treatment requirement.

3. Impact Test requirement on Weld and HAZ

4. Production Test Coupon Requirement

5. Shell development drawings showing interference, if any, with nozzles and other attachments (for columns, reactors and other equipment with large number of nozzles and attachments)

6. Hydrotest pressure at shop and site.

7. Details of all internal and external attachments.

8. Painting details including surface preparation.

9. List of spares for erection and commissioning and two years of operations.

WPS, PQR, Welder qualification records

Quality assurance plan

Inspection and test plan

Hydrotest procedure with sketch (sketch for showing supports for tall columns)

Any other test procedure if applicable (e.g. helium leak test procedure, etc.)

Painting Specification

Transportation sketch showing location of supports for transportation

Any other document called for specifically by purchaser

Drawing and document schedule

Purchase specification for bought out components including plates, forgings, pipes, flanges etc.

For equipment coming under the purview of Indian Boiler regulations, it shall be vendor’s responsibility to get approval from IBR authorities pertaining to design, material of construction, fabrication, inspection and testing.

For equipment coming under the purview of Static and Mobile Pressure Vessels rules, it shall be vendor’s responsibility to get approval from Chief Controller of Explosives pertaining to design, material of construction, fabrication, inspection and testing.


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All documents referred above shall be submitted for approval to the PURCHASER on or before schedule date.

No subsequent revision may be issued to the fabrication shop without prior review by the PURCHASER.

4.7 Mechanical Design

4.7.1 Design Pressure

The design pressure at the top of the vessel shall be as stated on the Mechanical Data Sheets. The static head due to contents (min. S.G.=1) shall be added in all cases.

Vessels shall be designed and protected against vacuum only when the vessels are to be actually subjected to external pressure during operation. Vacuum caused by emptying water after hydrostatic tests or condensing steam after steaming out the vessel, should not be considered as a design condition.

Vessel shall be designed for Steam out condition if specified on Mechanical Data Sheet.

4.7.2 Design Temperature

Design temperature shall be as specified on Mechanical Data Sheets. Two kinds of design temperature, one for the maximum design temperature (called as “Design Temperature”) and other for minimum design temperature(called as “Minimum design metal temperature” = MDMT) are specified.

If several pressure-temperature combinations are specified, the most stringent shall apply.

4.7.3 Corrosion Allowance

The corrosion allowance stated on the vessel data sheet shall be added to all exposed internal surfaces of pressure parts, non-removable internals.

Internal components welded to shell shall include corrosion allowance on all exposed sides.

Half the minimum corrosion allowance shall be added to the exposed surfaces for removable parts.

Internal fillet welds shall be sized to include the specified corrosion allowance on the throat thickness.

4.7.4 Minimum Thickness

4.7.4.1 Shells and Heads

The thickness of shells and heads excluding allowances for forming and corrosion shall be the greater of that required for loadings given in 4.7.6 or the following:

5 mm for austenitic steel

5 mm for C, C.Mn and low-alloy steel vessels up to and including 1200 mm inside diameter

7 mm for C, C.Mn and low-alloy steel vessels above 1200 mm inside diameter

10 mm plus cladding for clad vessels. (Minimum Clad thickness shall be 3mm. It shall not be considered while doing stress calculation)

4.7.4.2 Nozzles

The nozzle size, number of nozzles and flange rating shall be in accordance with Mechanical Data Sheet.

4.7.4.3 Skirts and Leg Supports

Skirt or leg supports shall be designed for specified loads, but shall not be less than 6 mm thick.


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4.7.4.4 Internals

Tray support rings, etc. shall be designed for specified loads but shall not be less than

6 mm thick plus twice the specified corrosion allowance for carbon steel

6 mm thick for high alloy and stainless steel.

4.7.5 Heads, Transitions and Discontinuities

Thickness of the formed heads shall be indicated on Mechanical Data Sheet / Drawings as Minimum After-Forming (MAF).

Cylindrical transitions shall be toriconical sections when any of the following conditions apply:

Vessel is in cyclical service.

The section is subject to a major support reaction (for example skirt to cone attachment).

Shell thickness is over 30 mm.

The required reinforcing is not integral with the shell.

4.7.6 Calculation

The VENDOR shall provide detailed calculations to justify the design. Calculations shall be fully detailed showing all working and references used and shall be presented in such a manner that they can be easily checked.

All calculations, except those for weights and Centre of Gravity, shall represent the vessel in the fully-corroded condition.

The VENDOR shall establish weights (shipping, empty, operating and test) and the locations of the centre of gravity (empty and operating).

Vessels and their supports shall be designed for the most severe condition of coincident loading, as defined below and in paragraph 4.7.7 :

The effects of external primary mechanical loads plus design pressure and the effects of secondary stresses due to differential thermal expansion shall be investigated, and the resulting combined stresses and deflections shall be evaluated, if specifically asked in Mechanical Data Sheet.

Material tolerances shall be applied to give the most conservative design, e.g. pipe thickness shall be minimum for mechanical design, plate thickness shall be maximum for weight calculations. Design calculations for metal clad vessels shall be based on nominal thickness of the base material.

Where the vessel is in cyclic service, fatigue shall be considered.

4.7.6.1 Definitions

Normal Operation Includes design pressure, operating vessel dead load, operatingcontents of vessel, superimposed external loads and any other applicable operating effects (such as unbalanced pressure,thermal induced piping or internal strain loading and impact loads) all combined with wind or earthquake.

Shop Test Includes test pressure, test load of vessel and attached equipment and weight of test contents in the vessel and in such other equipment as may be affected.

Field Test All vessels shall be checked in fully corroded conditions for a field test with code required test pressure at the top.

Shipping Weight Completed equipment together with all fittings, covers, bolts, nuts and any removable/fixed internals, if installed.


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Empty Weight As shipping plus any internals / packings installed by others,insulation, fire-proofing, platforms, ladders, instruments and percentage of attached pipe work.

Operating Weight As empty plus operating liquid and/or packings.

Shop Test Weight As fabricated weight plus weight of water to fill.

Field Test Weight As empty less insulation and internals/packing plus weight of water to fill.

Operating dead load The weight of the empty vessel, plus internal and external attachments, insulation, operating fluid and content weights.

Test dead load The weight of the empty vessel without internal or external attachments plus weight of water. Water volume shall equal the volume of the vessel.

Erection dead load The weight of the empty vessel without insulation, removable internals, or external attachments.

4.7.6.2 Units

Calculations may be made in the units of choice. When calculations are made in units other than SI, the result of all principal steps and the final results shall additionally be expressed in SI units:

Calculations shall use metric units as follows:

Dimensions mm

Pressure bar g

Stress Kg/mm2

4.7.7 Loading

The following load conditions and combinations shall be considered:

4.7.7.1 Load Conditions

Operation Design pressure

Hydrostatic pressure of liquid head

Operating dead load

External attached equipment

insulation and fire proofing

Live loads

Any other operating effects such as unbalanced pressure, thermal, etc.

Test (In the installed Test pressure

Position & corroded Hydrostatic pressure of liquid head

Condition) Test dead load

Equipment and external attachment test loads


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Erection 1 (Lifting) Erection dead load

If required, including weight of

Internals

Insulation

Equipment and external attachments (platforms, ladders, piping, etc.)

(A shock factor depending on the method of rigging - but

minimum two (2.0) shall be used.)

Erection 2 Erection dead load (if specified including internals, ladders,

(Standing on foundation) platforms, piping and insulation, etc)

Wind or Seismic Load (also for external mounted equipment

and attachments

Empty Empty dead load

External attached equipment

Insulation and fire proofing

Live loads

It should be noted that critical load conditions may also occur when the vessel is not subject to internal pressure.

4.7.7.2 Dynamic Loads

The design for wind and seismic shall be performed for the geographical area of the installation site and shall be in accordance with applicable regulations. Dynamic loads shall be as prescribed in these regulations but must always take into account process induced loads.

Wind Considerations : Dynamic analysis shall also be carried out as per applicable standard design practice.

Seismic Considerations: for vessels Seismic coefficient method and for column response spectrum method shall be used.

Load combinations

Analysis shall be carried out for following conditions:

Load case Wind load Earthquake Load

Operation 100% 100%

Pressure test 30% NIL

Erection 1 70% NIL

Empty 100% 100%

Seismic and Wind loads shall be considered not acting concurrently


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Following guidelines shall be used while determining weight of trays, platform, ladders, etc.

Weight of Trays with Liquid 120Kg/m2

Weight of Caged Ladder 37 Kg/m

Weight of plain Ladder 15Kg/m

Maximum distance between two consecutive platform

5000m

Platform Projection Min 900mm for Column diameter upto 1000mm

Min 1200mm for Column diameter above 1000mm

Height of Platform for wind loads 0.5m

Weight of Platform 170Kg/m2

Platform shall be considered all round

To account for surface area of piping, platforms and other attachments fixed to the equipment the surface area of equipment exposed to wind shall be increased by 20%.

For columns, the static deflection at the top due to the wind load on the column shall be limited to 1/200 of the total height from the base plate.

4.7.7.3 Nozzle Loads

Local loads in shell and dished end around attachments such as nozzles, vessel support and lifting lug so on, shall be calculated.

The following generally accepted calculation procedure may be applied:

Bulletin of Welding research council No. 107 or 297

BS 5500 Appendix G

4.7.8 Internal Loads

Packing and bed support plates and their support rings and beams shall be designed for a load equal to the sum of:

Dry packing/bed weight

Equivalent in water weight of 35 % of the packing free volume

Pressure drop across the packing bed (if downward gas flow)

The design shall provide not less than 65 % support plate free area.

Deflection of internal support beams or other loaded members shall not exceed 1/1000 of span.

4.7.8.1 Basic Allowable Stresses

Basic allowable stresses for pressure parts shall be established by ASME Section II Part D.

Basic allowable stresses for non-pressure parts shall be the lower of 1/3 of the ultimate tensile strength (at room temperature) or 2/3 of the yield strength (at design temperature) or that producing a creep rate of 1 % in 10 000 hours, except that the following non-pressure parts shall be designed using the stress for pressure parts:

Welds attaching non-pressure parts to pressure parts.

Internals, whose failure would have serious consequences such as catalyst support grids.


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Internals, whose performance would be affected by deformation, such as liquid distributors and their supports.

When creep becomes a design consideration, VENDOR shall submit detailed design to PURCHASER for review.

The calculated stresses for the design conditions shall be limited to the following:

Erection basic allowable stress at ambient temperature and uncorroded thickness

Operation/empty basic allowable stress at design temperature and corroded thickness

Test 90 percent of the minimum specified yield stress at test temperature and corroded thickness for pressure parts & 1/3 of the basic allowable stress at test temperature and corroded thickness for non-pressure parts

For all design conditions the maximum allowable longitudinal compressive stress for shells including skirt to be in accordance with the applicable ASME Code.

5 MATERIALS

5.1 Material Selection

All material used in the vessels shall be of the type and grade specified on the Mechanical Data Sheet.

All material welded directly to pressure retaining parts shall be of the same material specification including impact requirements as the pressure retaining part.

All pipe material for pressure retaining parts with 12 inch NPS for CS and 8” NPS for SS and below shall be seamless .

Forged nozzle necks are preferred in lieu of pipe necks and shall be used when shell thickness is 40 mm or over.

All plates and forgings with a shell or flange thickness of 40 mm or greater (except ASME B 16.5 standard flanges) shall be ultrasonically examined in accordance with ASTM A435 and ASTM A388 (acceptance to ASME VIII, Div 2, paragraph AM-203.2).

Rimmed, semi-killed or structural quality steels shall not be used for pressure retaining parts.

Low hardness bolting shall be used for pressure bearing connections being in contact with the process fluid ( such as bolting for floating head covers) when this fluid may cause stress corrosion cracking (e.g. sour gas, caustic).

Gaskets shall be of asbestos free material suitable for the process and service conditions.

All materials shall be new and unused.

5.2 Material Substitution

Substitution of material may be made only upon written approval of the PURCHASER and provided there is no increase in cost. Approval must be given prior to commencement of work.

5.3 Material Identification

All materials shall be identifiable by means of certified legible markings relating to available, authentic material certificates during all stages of manufacture.

When metal stamping is done it shall preferably be on the long edge of each component as it leaves the mill. Plate rolling direction shall be indicated by suitable marking.


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Stockist certification will not be accepted.

The VENDOR shall maintain a system of material identification such that all materials used in the fabrication of pressure parts may be traced to the appropriate certification.

Where the material identification mark is unavoidably removed, transfer of the identification mark to pressure retaining parts shall be witnessed and documented by the third party inspector.

Unidentified material shall be rejected.

5.4 Alloy Lining

In this specification the term “Alloy lining“ is a general term that does not imply a specific fabrication or manufacturing process.

Alloy lining for shells and heads shall be integrally bonded cladding or weld deposit overlay.

When integrally clad vessels are used, a minimum of 10% of the clad surface , including no less than 1 square foot in each 10 square feet or fraction thereof, shall be ultrasonic examined for lack of bond after forming. The cladding shall be 100% ultrasonically examined in areas where attachments are to be welded directly to the cladding. Unbonded areas that cannot be encompassed by a 3 inch diameter circle shall be repaired by weld deposit overlay in accordance with the specification “Welding of Pressure Vessels“. When repairs in excess of 5% of the total examined area are required, the vessel shall be 100% ultrasonic examined. Repaired areas and weld deposit overlay at weld seams shall be 100% liquid dye penetrant examined in accordance with ASTM E165. Ultrasonic examination shall be in accordance with ASTM A578 S6 for spot examination or S7 for 100% examination.

Nozzles and manways in alloy lined portions of vessels shall be alloy lined and faced. The facing shall be made with weld deposit which is at least as thick as the lining when properly machined and of the same alloy as the lining. When nozzles are lined with ferritic type 405 or 410S stainless steel linings, the facing weld deposit shall be made with type 309 welding electrode. The facing weld deposit for austenitic stainless steel linings shall be made with type 309 welding electrode for the first pass, and the welding electrode for the second pass shall be of the same or similar analysis as the lining.

The method of lining connections, nozzles and manways shall be by integrally bonded cladding or weld deposit overlay.

Tubular liners are not acceptable.

6 MANUFACTURE

6.1 General

All workmanship shall be in accordance with best modern shop practice.

All work shall be true to specified dimensions within tolerances specified in the PURCHASER’s Design Standards.

When a difference in thickness exists between shell plates or plates and heads, the inside diameter shall be maintained, unless specified otherwise.

Tell-tale holes are required in all places where a lap or void occurs. This hole shall be deburred before assembling the joint.

Individual shell courses shall have their longitudinal seams welded separately before assembly with other shell courses or heads and shall be re-rolled if weld seam is peaked or inset.

To assure accurate fitting elevation location, particularly for columns or other long vessels, weld shrinkage shall be carefully estimated and allowed for the welding of circumferential seams, fittings, tray bars, insulation rings, etc.


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6.2 Additional Requirements for Fabrication of Stainless Steel

6.2.1 General

In addition to the general requirements of this specification the following additional requirements are applicable to stainless steel.

6.2.2 Materials Segregation

In storage areas, stainless steel and high alloy materials shall be stored together and physically separated from carbon steel materials. There shall be no contact between stainless steel and high alloy material to carbon steel.

6.2.3 Fabrication Conditions

Fabrication of stainless steel shall be carried out in clean workshop conditions dedicated to stainless steel working. There shall be no contamination from carbon steel.

Only stainless steel tools which have not previously been used for carbon steel work, may be used for stainless steel fabrication.

Arc air gouging is not permissible on stainless steel.

The use of carbon steel bridges for fit-ups is not permitted

6.2.4 Heat Treatment

Stainless steel components shall not be heated without prior written agreement of the PURCHASER, i.e. preheated, hot-formed or post-welded heat treated. Procedures for such treatments shall be submitted to the PURCHASER for review.

6.3 Reference Work Line

VENDOR´s fabrication drawings for each vessel shall indicate a permanent reference work line which shall be marked around the vessel perimeter on approximately 305 mm centres. Marks shall be both outside and inside except clad or weld overlay vessels shall be marked on outside only. All dimensions shall be from this line. For marking vibro-etching or low stress multi-dot stamping may be used.

The reference work line shall always be located at a tan line (the lower for vertical vessels).

6.4 Location of Weld Seams

Shells and heads shall be formed with the minimum number of welded seams.

Longitudinal and circumferential seams in shells and all seams in built-up heads shall be located to clear openings and their reinforcement by minimum three plate thicknesses or 50 mm, whichever is greater.

Permanent attachments shall be located to clear pressure retaining seams by at least one plate thickness. In cases where this is impractical, the PURCHASER´s written agreement shall be obtained. Any additional NDT specified by the PURCHASER in such cases shall be performed at the VENDOR´s cost.

Attachments shall be designed and placed so as to allow full inspection of seam welds.

Longitudinal seams in adjacent courses shall be staggered such that the distance between weld edges are not closer than the four times plate thicknesses or 100 mm, whichever is greater.

For horizontal vessels longitudinal seams shall be oriented above the equipment centre line. Joints shall not be located coincident with or across saddle supports.


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The layout of seams shall be such that longitudinal seams are not within the downcomer areas of trays or behind any obstruction that prevents inspection of these welds. Circumferential seams shall not fall on a tray ring or stiffener and shall be located not less than 100 mm above or below the tray ring or stiffener.

6.5 Heads

Where heads are formed by spinning, any spinning hole shall be increased in size to 300 mm diameter and an insert plate of same thickness as end, formed to correct radius shall be butt welded. This requirement is waived where a central nozzle is to be located in the end.

The knuckle region of semi-ellipsoidal and torispherical heads shall be examined by wet magnetic particle inspection technique (or liquid penetrant if stainless steel) and shall show freedom from cracks and splits after final forming.

Butt welds in heads which are fabricated from more than one plate shall be fully radiographed after all forming and heat treatment. One chordal joint in dished ends is acceptable, the joint shall be located in the middle one-third of the blank.

When fittings are to be installed in heads prior to assembly with shell, reference lines shall be centre marked (in accordance with paragraph 6.3) on head straight flange to locate fitting projection.

6.6 Nozzles

6.6.1 General

Nozzles and manholes shall conform to one of the following unless specifically shown on the drawings:

Flanged forged steel with or without integral reinforcement (long welding necks).

Fabricated construction using seamless steel pipe, rolled plate or forged steel necks with integrally welded bolting flange or welding neck flange. The joint between all necks and welding neck flanges shall have full penetration welds by means of double butt welds where size and accessibility permits or other means as shown on VENDOR´s fabrication drawings and approved by the PURCHASER.

Slip-on flanges class 150 lb may be used for access and inspection openings for design temperature up to and including 260°C and non-cyclic service. Not to be used for austenitic steel vessels and when the service is designated to be hydrogen, hydrogen sulphide, sour water or cyclic and in service where corrosion allowance exceeds 3 mm.

Slip-on flanges shall be drilled and tapped through the hub for air and soap suds testing of attaching fillet welds.

Cover plates for manholes, handholes and nozzles shall be forged of the same material and be of the same rating as the flange to which attached and drilled to suit.

Corrosion allowance on nozzle and manhole necks shall not be less than that of the vessel.

The thickness of the hub of a welding neck flange where it is welded to the nozzle shall not be less than that of the nozzle neck.

Flanges shall have the same inside bore as the nozzle neck.

Nozzle necks rolled from plate to the same specification as the vessel shell may be used for sizes 14” NPS & larger for CS and 8” NPS & larger for SS. The weld seam shall be full penetration butt welded and fully radiographed or U.T. inspected (see also 5.1).

Flanges in sizes NPS 24 and smaller shall conform to the requirements of ASME B 16.5. Carbon steel flanges larger than NPS 24 shall conform to ASME B 16.47.

All instrument connections shall be a minimum of 300 lb rating.


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Where two or more openings are provided for installation of equipment such as gauge glass, float controls, etc. They shall be set with a jig to prevent tolerances from being additive.

Couplings and other threaded connections other than air test holes in reinforcing pads are not allowed.

Pad-type nozzles shall not be used unless specified on PURCHASER’s data sheets.

All connections for nozzles, manways, handholes and so forth which do not extend into the vessel for internal connections are to be finished flush with the inside of the shell. The inner circumference of nozzle necks inside the vessel shall have 6mm minimum radius.

All access nozzles and other blanked-off nozzles shall be supplied complete with cover, bolts, washers, nuts and gaskets.

Where vessel wall thickness is 40 mm or over :

- reinforcement pads, backing plates or wrapper plates shall not be used except where wrapper plates are required for saddles.

- Self reinforced type nozzles shall be provided.

Bolt holes in external and internal flanges shall straddle the principal vessel centrelines unless otherwise stated.

6.6.2 Nozzle Attachment

Nozzles in vessel shell or heads shall be attached by full penetration welds and set through the vessel wall.

Nozzles inserted into or through cover plates shall be full penetration or partial penetration double welded. Attachment by fillet welds only is not permitted.

Set on type connection are permitted for nozzles size less than 3”NB for CS and SS. For alloy steel, all nozzles shall be set in type.

6.7 Reinforcement of Openings

Nozzles shall be reinforced per Code and PURCHASER´s Mechanical Data Sheet plus limitations of this specification.

Reinforcing pad material shall be the same as the shell or the head.

Thickness of reinforcing pads shall not exceed shell or head thickness.

Nozzle reinforcing pads shall have two ¼“ NPT drilled and tapped tell-tale holes to permit testing attaching welds with air and soap suds prior to final hydrostatic test. Drilled hole shall be deburred before attaching pad to vessel.

Where fillet welds on nozzle reinforcing pads are smaller than the pad thickness the corner of the pad shall be chamfered to provide a continuous surface with the face of the filled weld.

6.7.1 Nozzle Size

The minimum size of nozzles shall be 2 inch NPS (Nominal Pipe Size) for CS, Alloy steel, SS Vessels and 3” for cladded vessels.

6.7.2 Davits

Davits shall be provided for all manholes and for other blind flanges weighing 35 kg and over.

For vertical man-ways of Class 900 and higher and horizontal man-ways of Class 600 and higher the man-way davit is to be supplied to suit the class of flange.

Lugs for davits shall be full penetration welded.


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6.7.3 Flange Faces

Flange gasket seating faces shall be finished in accordance with ASME B 16.5, unless specified otherwise.

All facings shall be adequately protected against damage during fabrication, storage and/or heat treatment.

6.8 Gaskets

Gaskets shall be as per Mechanical Data Sheet.

6.9 Bolting

Stud bolts shall be fully threaded and long enough to accommodate a bolt tensioner when these are specified (allow one bolt diameter extra on length for bolt tensioner). Threads shall be UNC up to and including 1“ and unified 8 UN over 1“ (ASME/ANSI B1.1, Class 2A or Class 2B). All nuts shall be heavy series. (Three nuts required for stud bolt tensioning when a bolt tensioner shall be applied). The strength of studs shall be based on the cross-section of the smallest diameter. Studs shall extend 10 mm beyond each nut. Hard steel washers 6 mm thick shall be furnished under studs 1 ½ inches and larger.

Provision shall be made to use bolt tensioning equipment on flanged joints for hydrogen service.

Special consideration shall be given to the prevention of over stressing the flange or bolts during gasket seating, when Class 300 and lower flanges are used with spiral wound or metal gaskets.

Bolts and nuts shall be new and shall be lubricated with molybdenum disulphide before assembly.

VENDOR to supply 5 % spare bolts with nuts (min. 1 stud bolt with nuts per stud bolt size and per material grade) for each blanked off nozzle and manhole.

All internal bolting shall be SS material or better than the vessel internals.

6.10 Supports

6.10.1 Skirts

Skirts shall be in accordance with Standard Drawing “Skirt and Base Details“.

Skirts generally shall be attached to the underside of heads so that the skirt and shell plate centre lines coincide, after deducting corrosion allowance.

A toriconical transition shall be used when a cone to shell transition serves as a support point for the vessel.

Skirts shall be of sufficient length to allow 500 mm between the bottom of the head and the foundation. When skirt supports for columns and vessels are supported at ground level, there should be a minimum distance of 4 times the anchor bolt diameter between the outer flange diameter of the outcoming bottom head nozzles and the top plate of the anchor bolt chair or the top of the compression ring respectively.

In no case shall a skirt be positioned so that a vessel girth seam is covered.

The attachment weld between skirts and heads shall be designed for a smooth profile with throat thickness not less than the skirt thickness.

Carbon steel skirts of vessels built of solid alloy plate shall not be welded directly to the bottom head. An alloy ring of same quality as the head material shall be provided on the head for attachment to the carbon steel skirt. The thickness of this ring shall be calculated for vessel design temperature.

The length of the alloy ring shall be 600 mm minimum for vessels with design temperature of minus (-) 50° C or higher and 900 mm if the design temperature is lower than minus (-) 50° C.

For all grades of austenitic stainless steel heads, the alloy ring may be of 304 stainless steel.

6.10.2 Templates

Vessel manufacturer shall deliver template for each skirt supported vessel with more than 4 anchor bolts.


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One template shall be delivered in due time before casting of the vessel foundation at site. Notification shall be given to PURCHASER at least 5 working days before shipment so that PURCHASER's authorised representative can perform a dimensional check.

The gauge plate shall remain in the manufacturers workshop and shall be attached to the vessel skirt base ring for dimensional inspection by PURCHASER during final vessel inspection.

6.10.3 Leg Supports

If shown in Mechanical Data Sheet, the Leg supports shall be provided as per Standard Drawings.

6.10.4 Horizontal Vessels

Saddle supports shall be dimensioned in accordance with Standard Drawing. “Steel Saddles“.

Horizontal vessels shall be supported at two positions, on saddles that cover at least 120 degrees of the vessel circumference and shall have sufficient thickness or stiffeners to be suitable for design and hydrotest conditions. Material in the vessel support reinforcing pad shall be the same as in the vessel. A ¼” NPT vent hole shall be provided in each backing plate. Reinforcing pads shall be continuously welded to the vessel shell.

For vessels built of solid alloy steels, with shell thickness less than 10 mm and supported on legs or saddles, the carbon steel supports shall not be welded directly to the vessel shell. Alloy backing plates shall be used between the shell and the carbon steel support. Backing plate shall be made of the same material as the shell, except that for all grades of austenitic stainless steel shells, the backing plate may be of 304 stainless steel.

Where horizontal vessels are installed on concrete foundations, a sliding plate shall be furnished under the sliding support for shell expansion.

Long holes in sliding supports shall provide sufficient space for shell expansion.

6.11 Internals

6.11.1 General

All removable internals shall be designed to pass through the shell manhole and shall be in sections not weighing more than 50 kg.

Internal non-pressure removable connections shall have machine-faced plate flanges not less than 10 mm corroded thickness. Screwed connections are not acceptable.

All internal bolting shall be fitted with lock nuts, pins or other locking device to prevent loosening by vibration.

Demister pads shall be supported above and below by carbon steel or alloy (as appropriate) grids.

Unless otherwise specified, stiffeners shall be welded to shell with continuous weld seams.

6.11.2 Internal Piping

Internal pressure piping shall conform to the requirements of the service.

Internal non-pressure carbon and low alloy (5 % Cr maximum) steel pipe and fittings shall have the following minimum wall thicknesses and ratings:

Pipe in sizes 12“ and smaller: Standard weight

Pipe in sizes over 12“ : 9 mm wall minimum.


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Internal non-pressure pipe and fittings in high alloy-lined or clad vessels shall have the following minimum nominal wall thicknesses and ratings:

Pipe sizes 2“ and above: Schedule 10S or fabricated of 3 mm thick sheet.

6.11.3 VENDOR’ Scope

The VENDOR shall supply and install all internals as shown on the Mechanical Data Sheet, if not separately mentioned in exclusion. Internals shall be located and designed to permit full visual and non-destructive examination of all welds on and in the pressure retaining envelope.

The VENDOR shall furnish tray support clips and rings as well as down-comer bars and other parts which are to be welded to the inside of the vessel.

If required by the Purchase Order he shall install trays, baffles, pans, etc. in his shop. Details for attaching trays, baffles, pans, support clips and rings to the vessel interior, shall be in accordance with the tray support drawings and specifications listed on the Purchase Order.

The following requirements shall apply:

PURCHASER shall be notified before tray installation is started.

Trays shall not be installed until after any required postweld heat treatment is completed.

Adjustable weirs shall be installed at the weir height specified on the tray vendor's drawings.

Tray man-ways shall not be installed until after PURCHASER’s authorised representative has completed all inspections. All man-ways and gaskets shall be installed and the bolting fully tightened before shipment.

6.11.4 Provisions for Internal Lining

Where vessels are internally lined, internal features shall be designed to permit proper surface preparation, application of lining and verification of the integrity of the lining. Impingement plates, vortex breakers, etc. shall be removable if necessary to perform these operations. Such removable items should be of corrosion resistant materials, as specified on vessel data sheet and bolted on the vessel by welded lugs. Similarly, projecting nozzles forming dip pipes and stand pipes shall be internally flanged.

Careful consideration shall be given to lining requirements of internal pipes and flanges. All internal edges shall be rounded to a minimum radius of 3 mm and all weld spatter removed prior to blasting. Internal pipes shall be of compatible material to the vessel lining/cladding.

The surface finish of the vessel shall be approved as suitable for lining by the lining supplier.

6.12 External Attachments

Platform support clips, ladder support and guide clips and piping support clips shall be provided when required. Shell and/or head to which such support clips are attached shall be checked for local stresses induced by external loads to be provided by PURCHASER.

Large carbon steel attachments such as jacket closures, platforms and piping support clips, shall not be directly welded to vessels built of solid alloy steels, but shall be welded to an alloy pad of the same material as the shell and/or head. Such pads shall be continuously welded to the vessel.

Reinforcing pads for attachments carrying local loads shall be formed, fitted and welded so that pad closely follows the contour of the shell or head. Large size pads may require additional attachment welds within the area of the pad.

Unless otherwise specified, stiffeners shall be welded to shell with continuous weld seams.

Stiffening/insulation support rings on vertical vessels shall be provided with 25 mm diameter holes every 800 mm to facilitate drainage.

6.13 Vessel Accessories


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Each vessel shall be provided with:

Nameplate attached to nameplate bracket per Standard Drawing “Nameplate for Vessel“

Two lifting lugs per Standard Drawing “Lifting Lugs“ (on vertical vessels)

Earthing lugs as per Standard Drawing “Earthing Lugs“

Clips as per Standard Drawing “Insulation and Fireproofing Supports“, wherever required

Tailing Lug if specified

6.13.1 Name Plate

Completed vessels shall have a nameplate in accordance with Standard Drawing. Nameplates shall be of SS material installed on a nameplate bracket. The location of the name plate shall be as per Mechanical Data Sheet.

6.13.2 Lifting Lugs

All vertical shop fabricated vessels with an empty weight of over 100 kg shall be provided with lifting devices. Lifting lugs attached to the top of the vessel on the shell side or lifting trunnions attached to the shell above the vessel gravity centre shall be used depending on the vessel size and field erection capabilities. The construction shall be as specified on the vessel drawing/data sheet.

No lifting devices shall be provided on horizontal vessels, unless noted otherwise.

Lifting lugs and tailing lugs not shown on PURCHASER´s drawings shall be designed and supplied by the VENDOR. Calculations shall be submitted to the PURCHASER for approval. For all lugs designed by the VENDOR, including a check of the shell of local loads. Lugs shall be suitable for transportation and erection of the vessel to its operating position. A shock factor of “two“ shall be included in lifting lug calculations.

6.13.3 Earthing

Each vessel shall be provided with two earth lugs welded to supports.

On vertical vessels located 180° apart on skirt or legs.

On horizontal vessels, one on each saddle.

Girth flanges shall provide suitable electrical bonding across the flange connection. An external conductor shall be installed additionally when there is no conductivity through bolting and gaskets.

6.14 Welding

Welding shall be conducted in accordance with the applicable regulations, standards, codes and the applicable specification if specified.

Acceptance of welder/operator qualifications by the PURCHASER’s representative shall be obtained before any welding is performed on the equipment.

6.15 Heat Treatment

6.15.1 Code Requirements

Post weld heat treatment shall be performed for carbon steel, carbon manganese steel and low alloy steel as required by

- Design code


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- Specification for Welding of Pressure Vessels

- When specified on the Mechanical Data Sheet.

Post Forming heat treatment shall be performed for carbon steel, carbon manganese steel and low alloy steel as follows:

- hot formed materials if it was heated above normalising temperature it shall be normalised

- cold formed materials upto 16mm thickness shall be stress relieved and above 16mm thickness shall be normalised.

This heat treatment shall be performed after final operation.

Hot formed material of Austentic steel shall be solution annealed.

Special consideration shall be given to the forming temperature to avoid possibility of “hot cracking“ when hot forming is proposed for austenitic materials.

All materials shall be mechanically certified in the final heat treated condition.

6.15.2 Local Heat Treatment

Local heat treatment is not permissible without PURCHASER´s approval.

6.15.3 Treatment before and after PWHT

Flange faces and other machined surfaces shall be suitably protected against oxidation during heat treatment and shall be checked after heat treatment for warpage and distortion.

Internal surfaces of CS and low alloy steel vessels shall be cleaned after post weld heat treatment.

After post weld heat treatment of vessels no welding, hammering, grinding or deformation shall be permitted. If it is not possible to heat treat the complete vessel together with all welded attachments, this shall be stated at the initial proposal stage.

6.16 Tolerances

Fabrication and material Tolerances shall conform to the requirements of the code.

Dimensional tolerances for all vessels shall be in accordance with Standard Drawings.

Vertical vessels shall be checked for plumbness. After the ring sections have been assembled. The outside surface of the cylinder shall not vary from a straight vertical line more than 6 mm in any 6000 mm, nor more than 19 mm in the total length. When shell thickness is 200 mm or more, the variation from a straight line shall not exceed 31 mm in the total length.

The maximum out of roundness variance of vessels with internal trays any diameter may not vary plus or minus ½ % from the nominal diameter, with a maximum variation in diameter from nominal of 13 mm.

7 INSPECTION AND TESTING

7.1 General

All mandatory inspection requirements of applicable national, regional, local laws and regulations for the area of installation or as furnished by the PURCHASER have to be observed.

Acceptance criteria for weld defects shall be in accordance with the design code.


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7.1.1 PURCHASER’s Inspection

Inspection by the PURCHASER’s representative shall be in accordance with the VENDOR’s Quality/Inspection Test Plan that has been reviewed by the PURCHASER.

A visual and dimensional spot check by PURCHASER's authorised representative will be carried out prior to the hydraulic test and/or heat treatment or coating of the vessel, if any.

The VENDOR shall inform PURCHASER by fax at least 15 working days before the vessels are ready for inspection.

PURCHASER's authorised representative shall have the right to inspect all work in progress, both in the shop or in the field, to insure that proper workmanship, orientation, welding, testing, painting, etc. are being performed.

PURCHASER reserves the right to make preliminary intermediate and final inspection of both shop and field fabricated equipment.

The vessels as made available for the inspection shall be free from slag, dirt, oil, welding spatter and other foreign matter.

\

The pressure vessels presented for the inspection shall be subjected to a previous dimensional check by the VENDOR. The VENDOR shall prepare a dimensional record indicating the actual dimensions for each pressure vessel (including out of roundness; offset in welded joints, deviations from true alignment) and submit it to PURCHASER’s authorised representative. Any deviations from the specified tolerances shall be clearly marked in this record.

Manway and handhole cover hinges and hinge bolts shall be placed before the vessel is inspected. The hinge bolts shall fit so they can be turned freely by hand. Covers shall be swung open to ensure that no binding occurs.

All loose components included in the scope of supply of the pressure vessels shall be kept ready for the inspection.

Welds attaching welding pins or studs shall be tested by tapping with a light hammer.

Equipment or parts thereof and materials indicating irremediable or injurious defect, improper fabrication, excessive repairs and those that require more than two PWHT, or that they are not in accordance with the requirements of this specification shall be subject to rejection. They shall be subject to rejection at any time or place by the PURCHASER’s authorised representative if such conditions are discovered after acceptance of the items at the VENDOR’s plant.

Acceptance of shop tests shall not constitute a waiver of requirements to meet field tests under specified operating condition, nor shall shop inspection by PURCHASER relieve the Vendor of responsibility in case of later discovery of defective material or workmanship.

7.1.2 Test Records

The records listed below shall be available for examination by PURCHASER’s authorised representative at the time of inspection.

Mill test reports for pressure parts. The test reports shall state the specification to which the material complies, the heat, lot or melt number, the heat treatment (if any) given to the material, and the results of chemical analysis and mechanical tests. Certificates are acceptable for heat treatment information missing on mill test reports.

Certificates for bolting material

Welding procedure specifications, procedure qualification records and welder qualification tests

Radiographic films for required radiographic tests incl. the experts assessment and certificates for the results of any required magnetic particle, fluid penetrant, or other method of examination

Charts or other records of required hydrostatic, pneumatic, and other tests


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Pyrometer charts or other detailed records of heat treatment (postweld, normalising, heating for forming, etc.)

Dimensional check record

7.1.3 Additional Test and Inspections

The material tests and inspections outlined in this specification shall be made for quality assurance and for job records but shall not be considered to prohibit the Vendor from making additional tests or inspections to establish or improve shop procedures which will result in a satisfactory vessel. Results of the additional tests or inspections shall be for the Vendor’s internal use only.

7.1.4 Notice of Inspection and Examination

The Vendor shall furnish the necessary gauging and examination equipment and assist as required in all inspections and measuring operations.

7.1.5 Pre-Inspection Meeting

A pre-inspection meeting shall be held prior to the start of any fabrication work. The VENDOR shall produce a VENDOR’s Schedule, witness and hold points, weld procedures and any other documents concerning vessel fabrication as requested by the PURCHASER.

7.2 Air Testing of Reinforcing Plates

Reinforcing plates for nozzles, saddles and other external welded attachments shall have tell tale holes tapped ¼“ NPT to enable the entire attachment weld to be tested to 1.5 bar g minimum with dry air or light oil (before any post weld heat treatment and before hydrostatic test) using soap suds solution to detect leaks. After hydrostatic testing of the vessel, these holes shall be plugged with hard grease.

7.3 Hydrostatic Tests

7.3.1 General

Prior to pressure testing, equipment shall be thoroughly cleaned internally, and external surfaces shall be free of weld spatter, scale, and other foreign material. All exterior surfaces and welds subjects to pressure shall be clean and dry.

All vessels shall be hydrostatically tested in accordance with the design code prior to painting. The test pressure shall be held for 1 hour per 25 mm wall thickness with a minimum period of 1 hour.

Vertical vessels which are to be shop hydrostatically tested in the horizontal position shall be supported adequately to prevent local stresses from exceeding 90% the yield strength of the material.

Temporary supports or bracing during hydrostatic testing shall not be used.

7.3.2 Pneumatic Test

Where pneumatic (excluding reinforcing pad leak tests) and/or proof tests are required a procedure shall be submitted for the PURCHASER´s review.

When a field fabricated pressure vessel is to be pneumatically tested, the vessel seams shall be subjected to a 100 percent radiographic examination and all nozzle and attachment welds except welds attaching welding pins or studs shall be subjected to either a magnetic particle or liquid penetrant examination on all exposed surfaces before the pneumatic test is performed.


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7.3.3 Bolts and Gaskets

Service bolts and gaskets shall only be used for hydrostatic testing, when tightened to a predetermined tension using a procedure agreed with the PURCHASER.

Even for manholes, covers and heat exchangers, the pressure testing gaskets will not be replaced for delivery to site. The new gaskets required for these connections, whenever the joints have to be opened at site, shall be separately supplied and installed at site by others.

7.3.4 Testing Water Conditions

Hydrotesting of carbon steel vessels shall be performed using clean potable water. Sea water shall not be used.

Hydrotesting of stainless steel and high Nickel alloy vessels or those containing stainless steel lining or fixed internals shall be performed using clean water containing not more than 30 ppm chlorides.

After hydrotesting and careful draining stainless steel and high nickel alloy vessels, ithas to be assured that only swabbing and cold air blowing (no hot air drying) is applied.

8 PREPARATION FOR SHIPMENT

8.1 Preservation

Vessel to be cleaned, dried and free from all foreign matter after hydrotest.

Drying to consist of wiping dry and cold air drying of inaccessible areas. General hot air drying is not required and not allowed for stainless steel vessels.

All bolting shall be lubricated with molybdenum disulfide or equivalent before assembly.

All threaded connections such as test holes in reinforcing pads and slip-on flanges, etc., shall be filled with heavy grease.

8.2 Closures

All flange connections shall be protected with metal (min. 6 mm thick) cover plates attached with a minimum of four bolts

A rubber gasket shall be used between the flange and cover.

Permanent blind flanges or covers included in the VENDOR’s supply shall be bolted with service gaskets, stud bolts and nuts.

8.3 Loose Items

Service gaskets and/or spare parts shall be boxed or crated to prevent damage during shipment. Boxes or crates shall be marked to indicate the contents and equipment details.

8.4 Match-Marking

Should it be necessary to separate an unit into several parts of transport purposes, then all these parts shall be carefully match-marked to prevent any assembly errors.

8.5 Loading and Anchoring


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VENDOR to include for all items necessary for safe transportation of the vessel to site including temporary wooden transport saddles securely strapped or bolted to the vessel.

The VENDOR shall be responsible for loading and anchoring requirements to prevent any damage during shipment. Anchoring shall be inspected by PURCHASER’s Inspector. Partially fabricated equipment shall be braced as necessary to prevent any deformation that could affect construction in the field and open ends shall be covered to keep out dirt or any foreign matter during shipment.

Internals installed prior to shipment when required, are to be properly secured and protected.

VENDOR shall submit a loading diagram for review and comment by the PURCHASER, Diagrams shall be approved and cleared by the carrier to the final site.

8.6 Painting

External surfaces shall be prepared for painting and painted strictly in accordance with the Painting Specification.

Shop painting shall not be applied within 150 mm (6 inches) of any weld before PURCHASER’s inspection. Field welds of partially shop fabricated vessels shall not be painted until after complete erection and inspection.

Stainless steel equipment which does not require painting shall have the outside surface treated such that an uniform appearance is achieved.

Only stainless steel brushes, clean, iron free grit or stainless grit shall be used for cleaning alloy surfaces. All welding flux shall be completely removed.

Solvents used to clean or remove scale or oil shall be free of organic and inorganic chlorides.

De-rusting, painting as well as preservation of the pressure vessels shall be carried out after hydrostatic testing and the inspection by PURCHASER.

8.7 Marking

Vertical vessels shall be marked on the base and with 300 mm high vertical stripes and letter on the skirt, clearly indicating the north, south, east and west co-ordinates. The marking may be made on the shell near the bottom tangent line if the vessel is supported on legs or lugs.

Horizontal vessels shall have one end marked north, south, east or west to indicate vessel orientation.

The vessel shall be marked with the item number (character height about 200 mm). Removable pressure vessel components such as covers, hoods, bundles, floating heads, filter elements etc. shall be durably marked with the item number.

Care shall be taken to ensure that water insoluble ink or paint is used for markings.

When austenitic steel and high nickel alloy material (inconel, hastelloy, etc.) are to bemarked with fabrication or shipping information, the marking shall be done with water insoluble ink that does not contain sulphur, chlorides or metallic pigments.

Parts to be supplied loose such as spare parts shall be identified by means of a tag indicating the relevant part number as per the workshop drawing as well as the item number.

Warnings about lifting limitations shall be suitably marked on the vessel.

Vessels which have been stress-relieved shall have a warning printed on two sides which states:

“HEAT-TREATED VESSEL - NO WELDING PERMITTED“

in letters 150 mm high minimum. Similarly warning shall be given for vessels with an applied lining (epoxy,etc.)


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9 DATA FOLDER

Vendor shall submit the required number of copies of data folder as mentioned in purchase documents. This must contain the following information duly certified by Inspector:

Manufacturer’s Code Certificate

As-Built drawings of Equipment and design calculations

Rubbing of Name Plates

Material analysis and test certificate

PQR and Welder qualification reports

Heat treatment cycle records chart, Hydrotest record chart, PTC reports,

Test results (UT, RT, DP, MP, Hardness, HIC, Charpy V Notch, etc.)

Any other documents as required in purchase order.

specification_pressure vessel

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