3-12-8 pressure vessels low alloy steel

7/24/2019 3-12-8 Pressure Vessels Low Alloy Steel

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UOP LLC25 East Algonquin RoadDes Plaines, Illinois 60017-5017, USA

STANDARD SPECIFICATION

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PRESSURE VESSELSLOW ALLOY STEEL

Form QUA-03-5

DATE STATUS APVD AUTHD

27MAY11 Revised RGP RGP

Note:

Theinformationinthisdocumentisconfidentia

landthepropertyofUOPLLCandmustnotb

edisclosedtoothersorreproducedinanymann

erorusedforanypurposewhatsoeverwithout

itswrittenpermission.

1. TABLE OF CONTENTS

1. TABLE OF CONTENTS ........................................................................................................ 12. GENERAL ............................................................................................................................... 1

2.1 Scope ............................................................................................................................ 12.2 References .................................................................................................................... 22.3

Definitions .................................................................................................................... 3

3. DESIGN ................................................................................................................................... 43.1 General Requirements .................................................................................................. 43.2 Loading ........................................................................................................................ 43.3 Shells and Heads .......................................................................................................... 53.4

Vessel Supports ............................................................................................................ 6

3.5 Non-Pressure Containing Components Welded to Pressure Containing Components 73.6 Nozzles and Manways .................................................................................................. 73.7

Special Considerations for Low Temperature, Elevated Temperature or SevereCyclic Service ............................................................................................................ 10

4.

MATERIALS ........................................................................................................................ 10

4.1 General ....................................................................................................................... 104.2 Shells, Heads, and Other Pressure Containing Components ...................................... 164.3 Nozzles and Manways ................................................................................................ 164.4

Vessel Supports and Exterior Attachments ................................................................ 17

4.5

Internals, Internal Bolting, and Internal Supports ...................................................... 17

4.6 Gaskets ....................................................................................................................... 185. FABRICATION .................................................................................................................... 19

5.1 Details ........................................................................................................................ 195.2 Welding Processes and Electrodes ............................................................................. 21

5.3

Postweld Heat Treatment ........................................................................................... 235.4 Alloy Lining ............................................................................................................... 24

5.5 Tolerances .................................................................................................................. 296. NONDESTRUCTIVE EXAMINATION .............................................................................. 30

6.1 Shells, Heads, and Nozzles ........................................................................................ 306.2

Alloy Lining ............................................................................................................... 31

7. TESTING ............................................................................................................................... 337.1 Testing Medium and Conditions ................................................................................ 337.2 Procedure .................................................................................................................... 33

2. GENERAL

2.1 Scope

a. This Standard Specification covers the general requirements for design, materials,fabrication, inspection, and testing of chromium-molybdenum steel fusion weldedpressure vessels. Included are pressure vessels constructed of 1 Chromium (Cr) Molybdenum (Mo), 1Cr Mo, 2Cr 1Mo, and 3Cr 1Mo. Other Cr Moalloys and advanced, modified (e.g., vanadium modified), or enhanced versions ofthe listed materials are not included.

b. Exceptions or variations shown in the UOP Project Specifications take precedenceover requirements shown herein.


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edisclosedtoothersorreproducedinanymannerorusedforanypurposewhatsoeverwithout


2.2 References

Unless noted below, use the edition and addenda of each referenced document current onthe date of this Standard Specification. When a referenced document incorporatesanother document, use the edition of that document required by the referenced document.

a. American Society of Mechanical Engineers (ASME) Boiler and Pressure VesselCode, Section VIII, Division 1, Rules for the Construction of Pressure Vessels.

b. ASME Boiler and Pressure Vessel Code, Section I, Rules for the Constructionof Power Boilers.

c. ASME Boiler and Pressure Vessel Code, Section II, Materials, Part A, FerrousMaterial Specifications.

d. ASME SA-182, SA-234, SA-240, SA-263, SA-264, SA-265, SA-335, SA-336,SA-387, SA-388, SA-435, SA-578, and SB-127.

e. ASME Boiler and Pressure Vessel Code, Section II, Materials, Part C,Specifications for Welding Rods, Electrodes, and Filler Materials, SFA-5.4,SFA-5.5, SFA-5.9, SFA-5.11, SFA-5.14, SFA-5.23, SFA-5.28, and SFA-5.29.

f. ASME Boiler and Pressure Vessel Code, Section II, Materials, Part D,Properties.

g. ASME Boiler and Pressure Vessel Code, Section V, Nondestructive

Examination.

h. ASME Boiler and Pressure Vessel Code, Section VIII, Division 2, Rules for theConstruction of Pressure Vessels Alternative Rules.

i. ASME Boiler and Pressure Vessel Code, Section IX, Qualification Standard forWelding and Brazing Procedures, Welders, Brazers, and Welding and BrazingOperators

j. ASME Boiler and Pressure Vessel Code, Code Case 2235, Use of UltrasonicExamination in Lieu of Radiography, Section I and Section VIII,Divisions 1 and 2.

k. American Society for Testing and Materials (ASTM) A 36, A 193, A 194,A 240, A 283, A 285, A 516, A 913, A 992, E 165, and G 146.

l. ASME B31.3, Process Piping.

m. ASME B16.5, Pipe Flanges and Flanged Fittings NPS Through NPS 24.

n. ASME B16.47, Large Diameter Steel Flanges NPS 26 Through NPS 60.

o. ASME B46.1, Surface Texture (Surface Roughness, Waviness, and Lay).


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p. ASME B16.20, Metallic Gaskets for Pipe Flanges Ring-Joint, Spiral-Wound

and Jacketed.

q. American Welding Society (AWS) A4.2, Standard Procedures for CalibratingMagnetic Instruments to Measure the Delta Ferrite Content of Austenitic andDuplex Ferritic-Austenitic Stainless Steel Weld Metal.

r. American Petroleum Institute (API) Recommended Practice (RP) 582, WeldingGuidelines for the Chemical, Oil, and Gas Industries.

s. API RP 934-A, Materials and Fabrication of 2 Cr 1 Mo, 2 Cr 1 Mo V, 3 Cr 1 Mo, and 3 Cr 1 Mo 1/4 V Steel Heavy Wall Pressure Vessels forHigh-temperature, High-pressure Hydrogen Service.

t. API RP 934-C, Materials and Fabrication of 1 Cr Mo Steel Heavy WallPressure Vessels for High-pressure Hydrogen Service Operating at or Below825F (441C)

u. API RP 934-E, Recommended Practice for Materials and Fabrication of 1 Cr Mo Steel Pressure Vessels for Service Above 825 F (440 C).

v. API Publication 938, An Experimental Study of Causes and Repair of Crackingof 1Cr Mo Steel Equipment.

w. National, state and local governmental regulations and laws.

2.3 Definitions

a. Hydrogen Service

(1) Hydrogen partial pressure exceeding 50 psia {3.5 kg/cm2 (a)}.

(2) More than 90 volume percent hydrogen at any pressure level.

(3) Vessels or parts of vessels (and exchangers, e.g., shell or tube side) inhydrogen service are specified in the UOP Project Specifications

b. Severe Cyclic Service

(1) Cyclic service as defined in ASME B31.3, Section 300.2. Cyclic servicemay be mechanical, thermal, or a combination of both.

(2) Vessels in Severe Cyclic Service are specified in the UOP ProjectSpecifications


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3. DESIGN

3.1 General Requirements

a. The design, materials, fabrication, inspection, and testing of pressure vesselsshall comply with the requirements of ASME Section VIII, Division 1 (includingAppendix 31) or, when specified in the UOP Project Specifications, ASMESection I. Except as modified by this Standard Specification and the UOPProject Specifications, 1 Cr Mo and 1 Cr Mo vessels shall alsocomply with the requirements of API RP 934-C when operating at or below 825F (440 C), or API RP 934-E when operating above 825 F (440 C) and 2 Cr 1Mo and 3 Cr 1 Mo vessels shall comply with the requirements of API RP934-A when operating at or above 650 F (345 C). References to shouldwithin API RP 934-A, -C, and -E are replaced by shall.

b. Allowable stresses for materials shall be in accordance with ASME Section II,Part D.

c. The vessel designer shall be responsible for the stress and thermal analysis of thevessel and components.

d. The Contractor shall determine the need for and method(s) of performing anyspecial analyses above the minimum calculations required by the ASME Code.

e. Where "M.R." or MR is specified in the UOP Project Specifications, it

indicates that it is the Manufacturer's and/or Contractor's responsibility todetermine in compliance with applicable codes and standards, including anyadditional requirements specified in the UOP Standard Specifications, UOPStandard Drawings, and UOP Project Specifications.

f. Thicknesses specified are minimum, after forming and fabrication.

g. The vessel nameplate shall be fabricated from stainless steel and shall be visibleand accessible at all times. If located in an insulated area, the nameplate shall beplaced on standoffs so the insulation passes beneath it.

h. The location and design of miscellaneous or temporary attachments for liftingand handling the vessel, handling internals, support of platforms, ladders, piping,etc, is the responsibility of the contractor and/or the vessel fabricator.

i. Vessels that will be buried or mounded shall be protected against externalcorrosion by coatings, wraps, and/or cathodic protection.

3.2 Loading

a. The design temperature and pressure conditions specified on the UOP ProjectSpecifications are at the top of the vessel in its operating position. Pressures aregauge pressures, which are relative to atmospheric pressure at sea level{approximately15psia, 1.05 kg/cm2(a)}.


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b. Where "delta P vessel (total)" is specified on the UOP Project Specification, this

pressure drop shall be combined with any static head and the specified designpressure in order to determine the design pressure at the bottom of the vessel.

c. When design for external pressure is required, the minimum net externaldifferential pressure shall be full vacuum at sea level.

d. Wind and earthquake loads and the applicable load combinations shall bedetermined in accordance with the governing Code(s), standard(s), and the dataspecified in the UOP Project Specifications.

e. Vertical vessels shall be evaluated for vibration, including vortex shedding, dueto wind or other sources. Stress, deflection, and fatigue shall be evaluated whenan analysis is necessary.

f. Vessels and their supports shall be capable of supporting the vessel filled withwater in the erected position. The corroded (i.e., nominal thickness minus thecorrosion allowance) vessel shall be adequate for hydrotesting in the erectedposition.

g. The maximum deflection of trayed columns, other than under earthquakeloading, shall be no greater than the vessel height /200 (h/200), with a maximumdeflection of one foot (300 mm).

3.3 Shells and Heads

a. The design thickness shall not include any additional thickness provided as a

corrosion allowance nor any lining material applied for corrosion resistance, e.g.,weld deposit overlay or cladding.

b. The minimum design thickness, excluding corrosion allowance, shall be(D/1000) + 0.1 inches {(D/1000) + 2.54mm}, where D = nominal vessel insidediameter in inches (mm).

c. The effects of external primary mechanical loads plus design pressure and theeffects of secondary stresses, such as those due to differential thermal expansion,shall be a part of the design process, and the resulting combined stresses anddeflections shall be evaluated. It is the responsibility of the contractor to specifythe governing load cases and critical locations.

d. The knuckles of elliptical, torispherical, and toriconical heads and reducers, witha special emphasis on those in large diameter, low pressure services, shall bedesigned to prevent buckling under internal and external operating and pressuretesting conditions.

e. Pressure containing weld seams shall not intersect nozzles or nozzlereinforcement.

f. Vacuum stiffening rings shall be installed on the exterior surface of the vessel,and shall be insulated in a manner to maintain a temperature similar to that of thevessel shell. Internal stiffening rings may be considered if they do not


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(1) interfere with the process (e.g. fluid distribution or collection)

(2) interfere with installation, maintenance, or removal of internals, catalyst,packing, etc

(3) impede physical access within the vessel

(4) obstruct visual or non-destructive examination of welds

(5) collect fluids, create low flow areas, or promote corrosion or cokeformation.

3.4 Vessel Supports

a. Vessel supports (exclusive of allowances for corrosion) shall be designed towithstand the most severe combination of live and dead loads anticipated duringthe normal life of the vessel.

b. Provide a minimum of 1/16 inch (1.6 mm) corrosion allowance on vesselsupports.

c. Stresses due to differential thermal expansion and frictional forces from slidingsupports shall be considered in the design.

d. Horizontal vessels shall be supported by two saddle supports fabricated to fit theoutside surface of the vessel within the applicable tolerances. Saddles shall

extend over a vessel arc of at least 120. Saddles shall not be placed over vesselgirth welds. A corrosion or wear plate shall be provided between the saddle andthe vessel shell. The corrosion or wear plate shall not be considered part of theshell or saddle for design purposes. The plate shall extend at least 2 inches (50mm) in all directions beyond the saddle. The corners shall be rounded to a radiusof at least 2 inches (50 mm). After removal of free moisture from between theshell and the plate, the plate shall be continuously seal welded to the shell aroundthe plates perimeter. At least one inch NPS vent hole shall be provided ineach plate section. Vent holes shall be tapped for future plugging. Vent holesshall remain open until the completion of pressure testing. The vent shall then beplugged with a material adequate for the operating temperature but not capableof retaining pressure.

e. Support legs shall be attached to the exterior surface of the vessel shell. The legsshall extend far enough along the shell to prevent local buckling of the shellbetween or above the legs. The legs shall extend a minimum of 6 inches(150mm) above the bottom tangent line of the vessel.

f. Skirt vent holes shall be provided at the top of the space enclosed by the skirtafter application of fireproofing and vessel insulation. The vent holes shall be aminimum diameter of 3 inches (75 mm), equally spaced, and a maximum of 6feet (1800 mm) apart. At least four vent holes are required. The vent holes shallbe unobstructed at all times.


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g. Provide at least one access opening in skirts supporting vessels from below.

h. Openings in support skirts shall be reinforced.

3.5 Non-Pressure Containing Components Welded to Pressure Containing Components

Load bearing welds attaching non-pressure containing parts to pressure containing partsshall be designed using the same allowable stress basis for primary membrane tensile,compressive, and shear stresses as required for pressure containing components of thesame material.

3.6 Nozzles and Manways

a. General

(1) Threaded fittings, unions, couplings, and tapped holes are not permitted.

(2) The minimum nozzle size shall be 1 inch nominal pipe size (NPS) exceptthat for alloy lined nozzles the minimum size is 1-1/2 inch NPS.

(3) When the inside diameters of nozzles and manways are specified, theyshall be considered as minimum. In lined areas, the specified insidediameter is the inside diameter of the finished lining. Connections thatreceive equipment shall be checked to ensure that the inside diameter islarge enough and the flanges match

(4) Flanges and bolts shall be analyzed to ensure that they are not overstressedduring gasket seating. Overstressing is more likely to occur when Class300 and lower flanges are used with spiral wound or metal gaskets.

(5) Nozzles and manways shall not be located in tray downcomers.

(6) Flanges shall not be located inside of vessel support skirts or otherconfined areas.

(7) Nozzles and their reinforcement in heads shall be entirely contained withinthe center 80 percent of the head unless a detailed analysis is performed tovalidate the design considering all mechanical and thermal loadings.

b. Flanges

(1) Flange classes are specified in accordance with ASME B16.5 or ASMEB16.47 Series B. Flange classes listed in the UOP Project Specificationsare based upon design pressure and temperature conditions only, and donot account for other loads. The final design of all flanges shall accountfor gasket seating and external loads. Differential thermal expansion ofdissimilar joints and transient thermal conditions such as start-up/shutdownand operational upset shall be accommodated.


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(2) Class 150 flanges shall not be used for design temperatures over 700F

(370C).

(3) Class 300 flanges (minimum) shall be used for instrumentation pipecolumn attachments to the vessel. This requirement does not apply toindividual transmitters or indicators mounted on pipe columns or directlyconnected to the vessel.

(4) Slip-on flanges are not recommended for any service, and are onlypermitted when in accordance with all of the following:

(a) The hydrogen partial pressure (design) does not exceed 50 psia {3.5kg/cm2(a)}.

(b) The fluid service is not corrosive {defined as a required corrosionallowance of 1/8 inch (3mm) or less} to the materials ofconstruction.

(c) Postweld heat treatment is not specified in the UOP Project orStandard Specifications.

(d) The flange is not in a severe cyclic service.

(e) The design temperature does not exceed 500F (260C) and theMinimum Design Metal Temperature (MDMT) is not below 20 F(-29C).

(f) With the exception of nozzles less than 4 inches NPS not subjectedto external loads and manways, all flanges are Class 150. Fornozzles less than 4 inches NPS not subjected to external loads andmanways, flanges do not exceed Class 300.

(g) Slip-on flanges, when permitted, shall be double welded and ventedthrough the hub with 1/8 inch (3 mm) diameter pre-drilled ventholes.

(h) The welds joining the flange to the pipe shall be visually and liquiddye penetrant examined.

(5) Lap joint flanges shall not be used in severe cyclic services.

(6) The design of slip-on and lap joint flanges subjected to external loads dueto piping displacement, shall consider the stress intensification factors(SIFs) from ASME B31.3 appendix D. The design for primarymechanical loads shall limit the nominal stress in the neck of the flange toone-fourth (1/4) of the code allowable stress at temperature unless adetailed analysis is performed.


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(7) Flanges that are intended for use with spiral wound gaskets shall have a

flange surface finish of 125 microinch Ra minimum to 250 microinch Ramaximum. Flanges intended for use with other gaskets shall have a flangesurface finish within the optimal range for the specified gasket. Finishesshall be judged by visual comparison with surface finish roughnessstandards conforming to ASME B46.1. Flange finishes shall be protectedfrom damage during fabrication, heat treatment, shipping, storage andinstallation.

(8) Ring joint flanges shall have a flat bottom groove with the intersectionbetween the bottom and sides of the groove machined to a smooth 0.125-inch (3 mm) minimum radius.

(9) Flanged thermowells and other connections joining dissimilar materialsrequire special consideration. The flange Class for both materials shall bedetermined and the higher Class used for both flanges.

(10) Flanges designated as special in the UOP Project Specifications andother flanges that are not within the scope of ASME B16.5 or ASMEB16.47 shall be designed in accordance with ASME Section VIII, Division1, Appendix 2 and Appendix S. The bolt and gasket materials to be used inthe design of these flanges are as noted in the UOP Pipe Class specified forthe connection. The applicable UOP Pipe Class is that specified for theconnected piping on the UOP Piping and Instrument Diagram (P&ID).Where there is no connected piping (e.g., a manway), use themiscellaneous connections Pipe Class specified for the vessel on the UOP

P&ID. As a minimum, the flange shall be designed for use with spiralwound gaskets.

(11) The Contractor shall be responsible for the compatibilityof all flangesmating with piping, instruments, or equipment.

c. Details

(1) Either an integrally reinforced nozzle or balanced integral reinforcement inboth the nozzle neck and vessel is required for hydrogen service and ispreferred for all services. Built-up construction using pipe or rolled platewith a flange and reinforcing pad ispermissible for non-hydrogen services.Gussets are not permitted.

(2) When the design pressure exceeds 1000 psig {70 kg/cm2(g)} or the shellthickness exceeds 2 inches (50 mm), 4 inch NPS and greater nozzles shallutilize an integrally reinforced forging in accordance with ASME SectionVIII, Division 1, Figure UW 16.1 (f-1), (f-2), (f-3), or (f-4). Nozzlessmaller than 4 inch NPS shall be integrally reinforced.


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(3) When the design temperature is within the materials creep range {above

800F (425 C)}, 4 inch NPS and larger nozzles shall utilize integrallyreinforced forgings in accordance with ASME Section VIII, Division 1,Figure UW-16.1 (f-1) or (f-4). Balanced reinforcement between the nozzleand the shell, designed to minimize the creep strain concentrations at thejunction, is preferred. Nozzles smaller than 4 inch NPS shall be integrallyreinforced.

(4) External reinforcing pads shall have a minimum of one 1/4 inch NPS venthole. Pads for nozzles greater than 16 inch NPS shall have a minimum of 2vent holes and pads for nozzles in excess of 36 inch NPS shall have aminimum of 4 vent holes. Pads installed in sections shall have at least onevent hole per section. Vent holes shall be tapped for future plugging. Ventholes shall remain open until the completion of pressure testing. Thematerial used for plugging shall be adequate for the operating temperaturebut shall not be capable of retaining pressure.

3.7 Special Considerations for Low Temperature, Elevated Temperature or SevereCyclic Service

For design temperatures of -20F (-29C) and lower or 800F (425C) and higher, orsevere cyclic services, the design details for nozzles, supports, and other attachments tothe vessel pressure containing components shall be free of high local stressconcentrations, e.g., sharp discontinuities, immediate changes of direction of a surface,notches, weld undercuts, etc. Internal and external fillet welds shall be ground to asmooth and generous concave contour. Notches, weld undercuts, etc. shall be removed.

4. MATERIALS

4.1 General

a. Pressure vessel materials shall be in accordance with ASME Section II, Part A.Non-pressure parts may be in accordance with American Society for Testing andMaterials (ASTM) Specifications. ASME Specification numbers are prefixed bySA and the corresponding ASTM Specification numbers are prefixed by A.

b. Low temperature services {per the applicable Minimum Design MetalTemperature (MDMT) and the maximum specified impact test temperature} may

utilize materials pretested and certified for low temperature applications. Thesematerials are listed in ASME Section VIII, Division 1, Table UG-84.3.

c. All material used in the vessel(s) shall be new.

d. All materials shall be vacuum degassed.

e. The use of Carbon-Molybdenum alloys is prohibited.


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f. The thickness of components made of 1 Cr Mo or 1 Cr Mo shall not

exceed 4 inches (100 mm). The thickness is measured at welded joints; tubesheets, integrally reinforced nozzle bodies, flanges, etc may exceed 4 inches (100mm) in thickness. If the thickness exceeds 4 inches 100 mm), 2 Cr-1 Momaterial shall be used for the entire vessel.

g. Each plate, forging, and other product form shall be legibly stamped or stenciledshowing specification number, grade, and class. When metal stamping is used, itshall be on the long edge of each component as it leaves the mill. Metalstamping on rolled surfaces shall be done with a "low stress" stamp. Markingsshall be protected from erosion, wear, or other events that may render themunreadable.

h. When the room temperature tensile strength of pressure containing componentsand welds is not limited to a lower value by the applicable product specification,it shall not exceed 100,000 psi (7030 kg/cm2).

i. Accelerated cooling from the austenitizing temperature is acceptable wherepermitted by the applicable product form specification.

j. When the component thickness exceeds 2 inches (50mm), specimens formechanical testing shall be taken at the thickness (T).

k. The material mechanical properties required by the product form specification,the ASME Code, UOP Standard and Project Specifications and Drawings, andall referenced documents shall be met in the as delivered and, as required by

API RP 934-A, -C, or E ( as applicable), the minimum and/or maximumpostweld heat treated condition(s)

(1) For the purposes of this paragraph, the following definitions apply;

(a) As Delivered Subjected to the heat treatments required for theproduct form as supplied from the material supplier, e.g., normalizedand tempered. Any required tempering is always included.

(b) Minimum Postweld Heat Treated Condition As defined byAPI RP 934-A, -C, or E (as applicable) with the additionalrequirement that the minimum permitted temperature for the shortestpermitted duration for each thermal exposure is used. Does notinclude allowances for shop or field repairs.

(c) Maximum Postweld Heat Treated Condition As defined byAPI 934 A, -C, or E (as applicable) with the additionalrequirement that the maximum permitted temperature for the longestpermitted duration for each thermal exposure is used. Includesallowance for one shop and at least one future field heat treatmentfor repairs or alterations.


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(d) Larsen Miller Parameter (LMP) A means of characterizing the

cumulative effect of elevated temperature exposures on the materialmechanical properties. The parameter is defined as:

LMP =T x (20 + log t) whereT = Temperature (K) and t = time in hours

(2) The vessel fabricator shall provide the minimum and maximum (as definedin paragraph 4.1.k(1)(b) and (c)) anticipated postweld heat treatmentconditions to be performed by the vessel fabricator to the steel supplier.This information will be used in testing the steel to confirm that therequired mechanical properties will be maintained under all anticipatedthermal treatment conditions. This information may be transmitted ineither of the following forms.

(a) The Larsen Miller Parameter for the total accumulated thermalexposures performed by the vessel fabricator for the maximum andminimum postweld heat treated conditions.

(b) A detailed description of the minimum and maximum temperature,minimum and maximum exposure time, and number of exposuresfor each thermal condition.

The fabricator shall also clarify that the transmitted information includes allexpected fabrication thermal exposures, allowance for one extra shop exposure,and allowance for at least one future exposure for repairs or alterations. The

conditions of the future exposures (maximum temperature and hold time) shallalso be listed. The maximum temperature and hold times shall permitcompliance with all referenced Codes, specifications, and other applicabledocuments.

(3) The steel supplier shall prepare coupons of each heat of each as deliveredproduct form {small forgings may be tested on a lot basis as defined byASME Section VIII, Division 1, paragraph UG-84(e)(2)} and subject thecoupons to heat treatment simulating the minimum and maximum postweldheat treated conditions supplied by the vessel fabricator. Simulation maybe by duplication of the thermal treatments or by application of the Larsen Miller Parameter formula, as agreed by the owner and the steel supplier.

(4) The steel suppler shall test the heat treated coupons, evaluating themechanical properties required by the product form specification, ASMECode, UOP Standard Specification, UOP Project Specification andDrawings, and all referenced documents. The results shall comply with therequirements of the listed documents.

(5) The steel supplier shall provide the results of the mechanical property testsin the as delivered and, as required by API RP 934-A, -C, or E (asapplicable), the minimum and/or maximum postweld heat treated conditionto the fabricator.


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(6) The vessel fabricator shall ensure that the actual thermal exposures (e.g.,

heat treatments, hot forming) are within the parameters supplied to the steelsupplier and that an allowance for the defined number of future exposuresand conditions (temperature and time) remains. The maximum permittedfuture conditions (temperature, duration, and number of exposures) shall besupplied to the Owner.

l. Charpy V-notch impact testing is required for all pressure containingcomponents and welds from each procedure, welder/welding operator, andwelding position. Impact tests shall be in accordance with the requirements ofASME Section VIII, Division 1, except that there shall be no exemptions fromimpact testing. 1 Cr Mo and 1 Cr Mo shall also meet the requirementsof API RP 934-C. 2 Cr 1 Mo, 3 Cr -1 Mo, and the vanadium modifiedversions of these alloys shall be impact tested at -20F (-29C) and the averagevalue of three specimens shall not be less than 40 ft-lb (55 Joules) with no singlevalue below 35 ft lb (47 Joules).

m. Plates and forgings over 2 inches (50mm) thick or used for pressure containmentin hydrogen service shall be:

(1) Ultrasonically examined with 100% scanning in accordance with thefollowing:

(a) Plates shall be examined before forming in accordance with ASMESA-435 including supplementary requirements S1.

(b) Forgings shall be examined in accordance with ASME SA-388 andASME Section VIII, Division 2, paragraph 3.3.4.

(2) Examined by either liquid penetrant (PT) or magnetic particle (MT) inaccordance with the following

(a) The entire surface of all forgings after finish machining.

(b) Formed plate surfaces to be welded, i.e., the weld bevel area, and aminimum of 2 inches (50 mm) of the neighboring surfaces.

(c) Formed plate surfaces where weld overlay will be applied.

n. When the operating temperature of 1Cr Mo or 1Cr Mo componentsexceeds 825F (440C), the following additional requirements apply:

(1) Plate materials shall be Class 1.

(2) Forging materials shall be Class 2.

(3) The carbon content of all product forms shall not exceed 0.13 weightpercent.


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(4) The heat analysis content of tin and phosphorous for all pressurecontaining components and welding consumables shall be less than orequal to 0.015% for tin and 0.007% for phosphorous. The percentagelimits are weight percent.

(5) The heat analysis carbon content of all 1Cr Mo and 1Cr Mowelding materials shall be not exceed 0.10 weight percent.

o. When the operating temperature of 2Cr 1Mo or 3Cr 1Mo componentsexceeds 650F (345C), the following additional requirements apply:

(1) Certified chemical analysis shall be provided for all components. Inaddition to the chemical analysis required by the applicable material

specification, analysis of Ni, Cu, As, Sn, and Sb shall be provided.

(2) Material shall have a J factor, defined as (Si + Mn) x (P + Sn) x 104, lessthan or equal to 100, where the concentrations are in weight percent. Inaddition, the nickel (Ni) content shall be equal to or less than 0.30% andthe copper (Cu) content shall be less than or equal to 0.20%.Concentrations are in weight percent.

(3) The fabricator shall provide a minimum pressurization temperatureapplicable for the anticipated life of the equipment at the design conditions.

(4) Impact testing shall be conducted as described in Paragraphs 4.1k. and l.Tests shall also be conducted at -20 F (-29 C) and the average impactvalues of the three specimens shall not be less than 40 ft-lb (54 Joules) withno single value below 35 ft-lb (47 Joules)

(5) Welding consumables shall be in accordance with the following:

(a) Mn and Si levels shall be maintained at the lowest possible levelsconsistent with good weldability.

(b) Each batch or heat of welding consumables and covered electrodes,including wire-flux combinations used in fabrication, shall beanalyzed for P, Sn, Sb, As, Ni, and Cu. Analysis shall be performed

on deposited weld metal. The temper embrittlement factor, X,

defined as (10 P + 4 Sn + 5 Sb + As)/100, shall be a maximum of 15parts per million. Element concentrations are in parts per million.In addition, the nickel (Ni) content shall be equal to or less than0.30% and the copper (Cu) content shall be less than or equal to0.20%. Concentrations are in weight percent.


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(6) Impact energy vs. temperature (transition) curves shall be developed from

samples {subjected to the minimum heat treatment (as defined in Paragraph4.1k) for the completed item} for each heat of plate, forging {small nozzleforgings may be tested on a lot basis as defined in the ASME SectionVIII, Division 1 Section UG-84(e)(2)}, pipe, and weldments representingeach batch or heat of welding consumables, covered electrodes, and wire-flux combinations for each welding process used in production welds.Testing of the production welds is not required.

(a) A minimum of eight sets of three impact tests {of material subjectedto the minimum (as defined in Paragraph 4.1k.) heat treatment forthe completed item} shall be conducted for each curve. Samplelocations shall be as specified by ASME Section VIII, Division 1.

(b) The impact tests shall be performed at different temperatures, butshall include the impact test temperature specified for the equipmentand -20 F (-29 C). The remaining test temperatures shall beselected so that the generated transition curve clearly defines thetransition zone and the upper and lower shelf. The maximum testtemperature shall be on the upper shelf energy level (defined as 100percent shear fracture) and the minimum test temperature shall be onthe lower shelf energy level (defined as zero percent shear fracture).The upper and lower shelves shall each be defined by at least twotest points, with at least four additional points defining the transitioncurve.

(7) Step Cool Tests shall be performed on samples {subjected to the minimum(as defined in Paragraph 4.1k.) heat treatment of the completed item} fromeach heat of plate, forging {small nozzle forgings may be tested on a lotbasis as defined in the ASME Section VIII, Division 1, Section UG-84(e)(2)}, pipe, and weldments representing each batch or heat of weldingconsumables, covered electrodes, and wire-flux combinations for eachwelding process used in production welds. Testing of the production weldsis not required.

(a) Step cooling shall be in accordance with the following temperatures,holding times, and cooling rates to the next lowest temperature:

Temperature F (C)

Holding time

(hours)

Cooling rate to the nexttemperature

F (C) per hour

1100 (595) 1 10 (6)

1000 (535) 15 10 (6)975 (525) 24 10 (6)

925 (495) 60 5 (3)875 (470) 100 50 (28)600 (315) Air Cool


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(b) Impact tests of each Step Cool Test sample shall be performed andtransition curves developed following the procedure in Paragraph4.1o.(5) of this Standard Specification.

(c) Acceptance criteria for the material shall be in accordance with thefollowing:

CvTr40 + 2.5CvTr40SC 50F (10C)Where

CvTr40 = Charpy V-notch 40 ft lb (54 Joules) impactenergy transition temperature of completelyheat treated specimens before step cooling.

CvTr40SC = The shift in the Charpy V-notch 40 ft lb (54Joules) impact energy transition temperatureafter step cooling.

4.2 Shells, Heads, and Other Pressure Containing Components

a. Shells may be fabricated from rolled plate, forgings, or pipe. Layered constructionis prohibited

b. Shells and heads shall be fabricated from the following materials. Other productforms shall be the equivalent grade.

ASME MaterialChemistry Plate Forging

1% Chromium 1/2% Molybdenum SA-387 Grade 12 SA-336 Grade F121-1/4% Chromium 1/2% Molybdenum SA-387 Grade 11 SA-336 Grade F11

2-1/4% Chromium 1% Molybdenum SA-387 Grade 22 SA-336 Grade F223% Chromium 1% Molybdenum SA-387 Grade 21 SA-336 Grade F21

c. When the shell or head is internally lined or the thickness exceeds 2 inches(50 mm) a calibration block for ultrasonic examination shall be provided. Theblock shall be in accordance with ASME Section V, Article 5 and shall include alining identical with the vessel lining.

4.3 Nozzles and Manways

a. Flanges shall be forged.

b. Flange material shall be ASME SA-182 of a grade corresponding to the vesselmaterial.

c. Pipe shall be seamless, in accordance with ASME SA-335, and of a gradecorresponding to the vessel material. Fittings shall be seamless, in accordancewith ASME SA-234, and of a grade corresponding to the vessel material.


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d. Plate used for the necks of built up nozzles and for flanges (when permitted byASME B16.5 or ASME B16.47) shall be ASME SA-387 of a gradecorresponding to the vessel material.

e. Austenitic stainless steel nozzles are not permitted.

f. Reinforcing pads shall be the same material as the shell.

g. Corrosion allowance for nozzles and manways shall be at least equal to thatspecified for the vessel shell.

h. Bolting materials shall be as required by the UOP Pipe Class specified on theUOP Piping and Instrument Diagram (P&ID). The applicable UOP Pipe Class isthat specified for the connected piping. When there is no connected piping (e.g.,a manway), use the miscellaneous connections Pipe Class specified for the vesselon the UOP P&ID.

4.4 Vessel Supports and Exterior Attachments

a. Material for rings, lugs, saddles and wear/corrosion plates, legs supportingvessels, and the upper three feet of support skirts welded directly to the vessel orto reinforcing rings welded to the vessel, shall be the same material as the shell.The remaining portion of skirts, if outside of the insulation, shall be ASTM A285, A 516 or the same material as the shell.

b. External and internal vacuum stiffening rings shall be the same material as theshell.

c. Base rings, reinforcement for skirt openings, saddle base plates, external lugs forplatforms, ladders, insulation supports, pipe supports, and other non-pressureparts welded to the vessel shall be the same material as the shell. Angles androds shall be ASTM A 36, A 913, or A 992.

d. External supports and attachments may be exposed to low ambient temperatures.The effects of this exposure upon material selection, stress analysis, fabricationdetails, etc shall be addressed.

4.5 Internals, Internal Bolting, and Internal Supports

a. The material for internals is specified in the UOP Project Specifications.

b. Internal support rings, lugs, brackets and other items welded to the shell shall bethe same material as the shell. In lined portions of the vessel, they shall becovered with alloy lining. When welded directly to the lining they shall be analloy corresponding to the lining.

c. Bolting for distributors, baffles, or other miscellaneous items not furnished by thetray supplier shall be the same or similar alloy as the internals.


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d. Drawings and instructions for fabrication and installation of tray and mesh

blanket supports attached to the vessel shall be furnished by the supplier of thevessel internals. The vessel manufacturer shall fabricate and install the vesselattachments in accordance with those instructions, and the UOP Project andStandard Specifications and Drawings.

e. As an alternative to welding rings, lugs, and brackets to the shell, they may beformed from weld build-up (using the same weld materials used for the vesselstrength welds) or integrally forged with the shell and covered with alloy liningwhere required. The transition to the shell shall be machined to a smooth andgenerous concave contour prior to the application of the alloy lining (if required).The top surface of the completed support rings (i.e., after application of alloylining, if required) shall be machined to provide a smooth, flat surface. Thewelding procedure, inspection and examination of weld build-ups shall be thesame as required for the vessel strength welds.

4.6 Gaskets

a. Gaskets shall conform to the requirements of the UOP Pipe Class specified onthe UOP Piping and Instrument Diagram (P&ID). The applicable UOP PipeClass is that specified for the connected piping. Where there is no connectedpiping (e.g., a manway), use the miscellaneous connections Pipe Class specifiedfor the vessel on the UOP P&ID.

b. Gaskets for use with raised face flanges shall be spiral wound per ASME B16.20with a non-asbestos filler material. In lined portions of the vessel, the winding

material shall be the same as the vessel lining. In unlined portions of the vessel,the winding material shall be a minimum of Type 304 austenitic stainless steel.Gaskets shall include an outer retainer ring. The outer ring may be carbon steel,protected against corrosion. When the operating temperature exceeds 850F(455C) the outer ring shall be Type 304 austenitic stainless steel. Gaskets forClass 300 and greater flanges, flanges over 24 inch NPS, and gaskets in vacuumservice shall have an inner retainer ring of the same material as the windings.Gaskets with an inner retainer ring shall also be used between flanges ofdifferent metallurgies with different coefficients of thermal expansion when theyoperate at an elevated temperature. The contractor shall verify the adequacy ofall gaskets considering potential buckling of the outer or inner retaining ring(s)and the windings.

c. The use of corrugated, double jacketed gaskets per ASME B16.20 may beconsidered for large diameter openings (over NPS 24 inch), especially when thesealing surface is vertical or when the surface to be sealed is not round (e.g.,multi-pass exchanger channel to shell closure gaskets).

d. Ring joint gaskets shall be per ASME B16.20.


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5. FABRICATION

5.1 Details

a. Shell and head joints, including nozzle attachments, shall be Type (1), fullpenetration, free of undercuts, double welded butt joints in accordance withASME Section VIII, Division 1, Section UW-3 and Table UW-12. The initialroot pass of double welded groove joints, including root tack welds, shall bechipped, ground, and/or gouged to sound metal on the reverse side beforewelding on that side. The back-chipped welds, welding groove, and plate edgesshall be magnetic particle or liquid penetrant examined to ensure that all cracks,pinholes, laminations, porosity, and other defects have been removed prior towelding on the reverse side. In cases where double welding is impractical, (e.g.the groove joint backside is not accessible for chipping or gouging and welding)the root pass shall be made by the Gas Tungsten Arc Welding (GTAW).

b. Pressure containing welds shall remain accessible for visual and nondestructiveexamination (e.g., radiography). Nozzles shall be located so that the nozzle,nozzle to vessel weld, and nozzle reinforcement are at least 3 inches (75mm)from all pressure containing shell and head welds. If intersecting or coveringpressure containing welds cannot be avoided, the nozzle shall be fully reinforcedand low stress welding details used (e.g., grind fillets to a smooth concaveradius). Pressure containing welds beneath reinforcement shall be groundsmooth and flush with the shell surface. All pressure containing welds shall be100 percent radiographed after forming and nozzle installation but beforereinforcing pad installation to a minimum of 6 inches (150mm) beyond the

nozzle to vessel weld or the limits of the reinforcing pad

c. Longitudinal and circumferential pressure containing welds shall not be locatedin tray downcomers, behind permanent internals, or in other areas that preventinspection from the inside of the vessel. Circumferential welds shall have aclearance of at least one inch (25mm) from tray support rings and welds andother circumferential attachments.

d. Nozzles shall penetrate through the shell, with the shell butt welded to thenozzle. Nozzles and their reinforcement (except the outer circumference ofreinforcing pads) shall be attached to the vessel with full penetration welds.Connections at air cooler header boxes may use a set on detail. Equipmentnozzles meeting the following criteria may also utilize a set-on detail:

(1) The nozzles are 3 inch NPS or smaller.

(2) The thickness of the component (shell, head, nozzle neck, blind flange, etc)to which the nozzle is attached exceeds 2 inches (50mm). This alsoapplies to nozzles welded to other nozzles.

(3) When reinforcement is required, the nozzle shall be integrally reinforced.


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(4) The nozzles are for instruments or another service without attached piping

and without significant imposed loads.

(5) The nozzles are not subject to significant cyclic (thermal or mechanical) orfatigue loadings.

(6) The base metal adjacent to the nozzle opening shall be thoroughlyultrasonic and magnetic particle examined to ensure that there are no flaws(e.g., laminations).

(7) The nozzle to shell weld shall be full penetration with an external filletground to a smooth, concave contour.

(8) The weld geometry shall permit full, non-destructive examination of thenozzle to shell weld in both the shop and the field, after operation.

(9) When spot examination of the vessel welds is required, at least onerandomly selected set-on weld shall be included in the examination.

(10) The nozzle to shell weld shall comply with the requirements for the otherpressure containing welds (e.g., double welded, back-gouged, nopermanent backing bars, etc).

e. Nozzles, manways, and handholes shall be cut flush with the inside surface ofthe shell or head. When an internal projection is necessary, the internalprojection shall not interfere with the process, internals, or the installation of

internals or other vessel contents. The inside edge of nozzles, manways, andhandholes shall be rounded.

f. Pressure containing shell, head, and radiographable nozzle welds shall belocated, designed, and ground to permit 100 percent on site radiographicexamination.

g. Pressure containing welds, internal attachment locations, and the method ofvessel support attachment shall accommodate full on-site external ultrasonicangle beam examination and visual inspection of head and shell welds with allinternal equipment in place. Welds shall be contoured to permit properinterpretation of ultrasonic examination.

h. When the operating temperature of 1Cr Mo and 1Cr Mo exceeds 825 F(440 C) and the materials do not comply with the requirements of Section 4.1n.,the weld details shall comply with the requirements of API 938, Figure 1,assuming a high MPCF.

i. Internal support rings shall be continuously welded to the shell on the top andintermittently welded on the bottom. Internal lugs and brackets shall becontinuously welded on the top and sides only. In hydrogen services all internaland external welds shall be full penetration, free of undercuts, through thesupport side of the joint.


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j. Lugs and rings for internal supports in lined portions of the vessel may be

welded directly to the lining only if the vessel is lined with weld deposit overlayor integrally bonded cladding meeting the requirements of ASME Section VIII,Division 1, Paragraphs UCL-11 (a) and (c).

h. In hydrogen services, all fillet welds (internal and external) to pressurecontaining components shall be ground to a smooth and generous concavecontour.

i. When austenitic stainless steel support rings are joined to an austenitic stainlesssteel lining, and the operating temperature is greater than 700F (370C),circumferential welds shall not be used. The rings shall continuously contact thelining and be supported by vertical lugs welded to the lining or shell.

j. Seams in supporting skirts shall be made with full penetration butt welds.Connections between straight skirts and vessel heads shall be made with asmooth flat-faced weld. The width of the weld shall be at least equal to the skirtthickness, and its height shall be approximately twice its width. When the shellthickness at the skirt connection exceeds 4 inches (100mm), the designtemperature at the skirt to shell connection is within the materials' creep range{above 800 F (425 C)}, or the skirt to shell junction is subject to cyclic loading,the joint details shall be as specified on the UOP Project Specification.

n. Details of flared skirts, lugs, and special vessel support systems are specified onthe UOP Project Specifications.

5.2 Welding Processes and Electrodes

a. Welding shall be by a metal arc process. Welding electrodes shall be inaccordance with ASME, Section II, Part C. Welding processes, materials, andprocedures shall comply with the requirements of API RP 582 except asmodified by this Standard Specification and the UOP Project Specifications.References to should within API RP 582 are replaced by shall.

b. The principal alloying elements and mechanical properties of the deposited weldmetal shall conform to the ASME requirements for chemical analysis andmechanical properties of the base metal, including any additional requirements inthe UOP Specifications. Each completed shell, head, and nozzle weld shall beanalyzed to confirm the required alloy content. Testing of the mechanicalproperties is not required. The method of analysis shall be sufficiently accurateto confirm that the measured alloy contents are within the specified limits. Theanalysis shall be of the inside weld surface. Each weld procedure, weldingposition, and welder/welding operator for each procedure and position they useshall be analyzed. Analysis shall also include each source of deposited weldingmaterials (e.g., reel of wire, box of rods, etc). If lining is required, the analysisshall be performed before application of the lining over the weld.


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c. Welding procedures and materialsshall comply with the requirements of

API RP 934-A, -C, or E (as applicable) with the addition that weldmentsrepresenting each batch of welding consumables, covered electrodes, and wire-flux combinations for each production welding process and samples from eachwelding procedure and qualified welding position (per ASME Section IX) istested. Welded samples shall use production plate.

d. All welding consumables shall be of the low hydrogen type. They shall bestored in accordance with the manufacturers requirements (e.g., remain in sealedpackaging prior to use, storage in warming ovens until use, etc). All materialsshall be stored and used in a manner that prevents exposure to moisture andinclusion of hydrogen in the deposited weld. The surfaces to be welded shall beclean, dry and free of contaminants. The weld procedure shall minimizehardenability and ensure that the weld meets all required properties, includingtoughness and ductility.

e. The Flux Cored Arc Welding (FCAW) process shall utilize an external shieldinggas and is not permitted for the root pass of joints made from one side. FCAWmay be used for the root pass of joints made from both sides only if it iscompletely removed prior to welding from the reverse side. FCAW is notpermitted for alloys containing more than 2 percent (nominal) chromium.

f. The Gas Metal Arc Welding (GMAW) process in the short circuiting mode(GMAW - S) may be used for the following applications only:

(1) The root pass for any material thickness.

(2) Complete groove or fillet welds provided that the wall thickness of thethickest portion of the joint does not exceed 1/4 inch (6 mm).

(3) Tack welds, temporary attachments, and other applications where the weldmade by this process is completely removed.

g. The Gas Metal Arc Welding process in the globular transfer mode ((GMAW-G)shall not be used.

h. The Gas Metal Arc Welding (GMAW) process in the spray transfer mode shallnot be used for the root pass.

i. When automatic submerged metal-arc welding (SAW) is used, alloying elementsshall not be added through the flux except to compensate for arc losses. Reuse ofburned flux is prohibited.

j. Covered welding electrodes (i.e., shielded metal arc welding SMAW) shall beof the low hydrogen coating type and shall be in accordance with ASME SectionII, Part C, SFA-5.5. Rod ovens, and other means as necessary, shall be used toensure that the rods remain dry.

k. Shielded Metal Arc Welding (SMAW) shall not be used for the root pass ofsingle sided groove welds.


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l. Electrodes with a G (General) designation shall not be used unless

(1) Mill certificates of the chemistry of each batch and lot used for productionwelds are submitted to, and approved by, the owner.

(2) A PQR is performed for each batch and lot used for production welds.

m. Bare electrodes for inert gas and submerged arc welding shall be in accordancewith ASME Section II, Part C and the following electrode specifications:

Welding Process Electrode Specification

Submerged Arc Welding SFA-5.23

Gas Shielded Arc Welding SFA-5.28

Flux Cored Arc Welding SFA-5.29

n. Submerged Arc (SAW) production welds shall be made with the same flux andfiller wire combinations and of the same type and brand used for the ProcedureQualification Record (PQR).

o. Backing strips, if used, shall be removed.

5.3 Postweld Heat Treatment

a. Welding directly to the base metal shall be completed prior to final heattreatment. All welding to alloy lining shall also be completed prior to the final

heat treatment unless a two layer weld overlay is used and the requirements ofParagraph 5.4c.(1) are met.

b. PWHT shall be performed by placing the vessel into a furnace and heatinguniformly. Local PWHT is permitted only for circumferential weld seams andonly when furnace PWHT cannot be performed. Local PWHT shall comply withthe following:

(1) The full circumferential band shall be uniformly heated and cooled.

(2) The soak band width shall be a minimum of the greatest width of the weldplus either the thickness of the weld or 2 inches (50 mm), whichever isless, on each side of the weld face.

(3) The heated band width shall be a minimum of the soak band width plustwice (RT)1/2on each side of the soak band.

(4) The gradient control band width shall be a minimum of twice (RT)1/2oneach side of the soak band.

(5) R is defined as the inside radius of head, shell, or nozzle neck and T isdefined as the thickness of the weld.


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c. Welded joints shall be heat treated immediately upon completion of welding.

The joint shall not be allowed to cool below 300 F (150 C) prior to heattreatment. Alternately, the weld and adjacent metal may be heated to 600 F(315 C), wrapped with insulation, and allowed to cool. Heat treatment may thenbe performed later.

d. All pressure containing components (regardless of size, thickness, or productform) and items welded to them shall be postweld heat treated. The heattreatment procedure shall be in accordance with API RP 934-A, API RP 934-C,API RP 934-E, and ASME Section VIII, Division 1 or, when specified in theUOP Project Specifications, ASME Section I, except that the hold temperaturefor 1 Cr Mo, 1 Cr - Mo, 2 Cr - 1 Mo, and 3 Cr 1 Mo components

shall be 1275F (690C) 25F (14C). When the operating temperature of 1 Cr

- Mo and 1 Cr Mo components exceeds 825 F (440 C) and thematerials do not comply with the requirements of Section 4.1n., the postweldheat treatment temperature for 1Cr - Mo and 1 Cr Mo, components shallbe in accordance with API Publication 938, Figure 1, assuming a high MPCF.

e. The alternate postweld heat treatment procedures permitted by ASME SectionVIII Division 1, Table UCS-56.1 (i.e., a reduced hold temperature for a greatertime) shall not be used.

f. Thermocouples shall be located on the inside and outside of the vessel surface,and placed to ensure that all portions of the vessel are properly and uniformlyheat treated, without the presence of detrimental thermal gradients.

g. During heat treatment the vessel shall be supported and stiffened to preventdistortions.

h. Flange facings shall be protected against oxidation during heat treatment.

i. Flame impingement is prohibited at all times.

j. When postweld heat treatment is required, one Brinell hardness reading shall betaken on the inside (except in lined portions of vessels) and on the outside ofeach shell section, head, and nozzle, and each longitudinal, girth and nozzleweld. The readings shall be taken after final postweld heat treatment. Noreading shall exceed a value of 225 Brinell. Readings shall be taken with aportable hardness tester calibrated at 225 Brinnell.

5.4 Alloy Lining

a. General

(1) The term "Alloy Lining" is a general term that does not imply a specificfabrication or manufacturing process.


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(2) Alloy lining for shells and heads shall be integrally bonded cladding or

weld deposit overlay. The required alloy and thickness are specified on theUOP Project Specifications.

(3) Strip lining is not permitted.

(4) Rings, lugs, brackets, and other attachments in the lined portion of thevessel shall be weld deposit overlayed unless they are fabricated from analloy corresponding to the lining.

(5) Tubular liners are not acceptable in nozzles greater than 1 inch NPS.Tubular liners may be used for smaller nozzles. The liner shall be weldedto the alloy facing at the flange end. Attachment of the liner at the insidesurface of the vessel shall be by an expansion (contraction) collar. Whendifferential thermal expansion/contraction between the liner and the nozzleis not a concern, the liner may be welded flush with the vessels insidesurface. The final details shall account for the sustained, transient, thermal(expansion/contraction), and cyclic stresses due to the intended operationof the vessel.

(6) In hydrogen service, nozzles with tubular liners welded on both ends shallbe vented with a 1/8 inch NPS hole, drilled from the outside to the OD ofthe liner. The vent hole shall be tapped for future plugging with a materialadequate for the operating temperature but incapable of retaining theoperating pressure.

b. Cladding

(1) Integrally bonded clad plate shall be fabricated in accordance with SA-263for corrosion resistant chromium stainless steel cladding, SA-264 forchromium-nickel stainless steel cladding, or SA-265 for nickel and nickelbased cladding.

(2) The bond between the cladding and the base metal shall be tested by andcomply with the requirement of the shear strength test as described in theapplicable cladding specification.

(3) When integrally bonded clad plate is used, the lining shall be cut back at allseams a minimum of 1/2 inch (13mm) from the edge of the weld bevel topermit welding of the base metal. The base metal welding procedure shall

ensure that the cladding bond is not damaged by the welding and thatcladding metallurgy is not incorporated into the base metal weld.Complete removal of the cladding shall be verified before proceeding withwelding of the base metal. The weld metal shall be ground flush and fullycovered with the applicable weld deposit overlay per Paragraph 5.4b.(4) ofthis Standard Specification. The weld deposit overlay shall be at least asthick as the cladding, but no greater than twice its thickness.

(4) Welding in conjunction with a clad lining shall be done with coveredelectrodes in accordance with ASME Section II, Part C and the followingelectrode specifications:


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ASME Specifications Electrodes

Cladding Applied Lining Alloy to Low

Alloy Steel

Alloy to Alloy

SA-263 SA-240,Types 405 or 410S

SFA-5.4 E309L SFA-5.4 E309L

SA-264 SA-240, Type 304 SFA-5.4 E309 SFA-5.4 E308SA-264 SA-240, Type 304L SFA-5.4 E309L SFA-5.4 E308L

SA-264 SA-240, Type 316 SFA-5.4E309Mo

SFA-5.4 E316

SA-264 SA-240, Type 316L SFA-5.4E309MoL

SFA-5.4 E316L

SA-264 SA-240,Types 321 or 347

SFA-5.4E309Cb

SFA-5.4 E347

SA-265 SB-127 SFA-5.11ENiCu-7

SFA-5.11 ENiCu-7

Note: When inert-gas shielded or submerged arc processes are used, stainlesssteel welding shall be in accordance with ASME Section II, Part C, SFA-5.9, with compositions similar to those listed above. Nickel-Copper alloy(Monel) welding shall be in accordance with ASME Section II, Part C,SFA-5.14 with a composition similar to that noted above.

(5) ASME Section VIII, Division 1, Part UNF, Appendix NF, Paragraphs NF-7 and NF-14 are mandatory for nonferrous types of cladding or weldoverlay.

(6) Internals may be attached directly to the cladding if the stress at theattachment under the design loads is less than one quarter of the allowablestress for the lug, ring, or bracket material. Attachment shall be performedafter postweld heat treatment. The heat input of the internals attachmentwelding procedure shall be such that the base metal is not affected by theheat and additional heat treatment of the base metal after the attachmentwelding is not required. Otherwise, the cladding shall be cut back at least inch (19mm) beyond the toe of the attachment weld and the lug, ring, orbracket shall be attached directly to the base metal. Complete removal ofthe cladding shall be verified before proceeding with welding to the basemetal. The attached material and the attachment weld shall be the samealloy as the lining or the shell to which it is directly welded. After

attachment directly to the base metal, the exposed area shall be completelycovered with weld overlay as described in Paragraph 5.4b.(4). of thisStandard Specification. The weld deposit overlay shall be at least as thickas the cladding, but no greater than twice its thickness.

(7) Large nozzles and manways utilizing built-up construction may useintegrally bonded cladding for the nozzle neck if the nozzle is fabricatedfrom rolled plate.


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c. Weld Deposit Overlay

(1) Weld deposit overlay may be applied by a single or multi-pass procedureand shall comply with the requirements of API RP 582 except as modifiedor amended by the UOP Specifications. The first pass of multipassaustenitic stainless steel weld overlays shall be applied prior to postweldheat treatment and shall be made with an electrode complying with therequirements of Paragraph 5.4b.(4). The remaining passes shall be madewith an electrode of the required lining alloy. Where internals will beattached to the lining, a two layer overlay shall be used; the second layershall be applied after completion of the final post weld heat treatment.When the second layer is applied after postweld heat treatment, thethickness of the first layer and the heat input of the second pass weldingprocedure shall be such that the base metal is not affected by the heat andadditional heat treatment of the base metal after the second layer is notrequired.

(2) The ferrite content of austenitic stainless steel weld deposits shall becontrolled to a WRC (Welding Research Council) Ferrite Number (FN) of3 (5 for Type 347) minimum to 8 maximum. With the owners approvaland in accordance with the provisions of API 582, paragraph 6.4.2.2a), thelower limit for Type 347 may be reduced to an FN of 3 if the fabricatordemonstrates and documents successful in service use, without hotcracking or failures, of welding consumables with an FN of 3 using theproposed welding procedure, materials (including brand), and similar basemetal thickness. FN control shall be by reference to the DeLong

Constitution Diagram for stainless steel weld metals. The limit definedabove shall be confirmed by thoroughly checking the final deposits prior topostweld heat treatment with a magnetic instrument calibrated inaccordance with the standard procedure defined in AWS A4.2. Readingsshall be taken from at least ten randomly selected locations on each shellcourse and head, and at least one location from each nozzle girth weld,vessel weld seam overlayed separately (e.g., between clad sections),overlayed support ring, bracket, or lug, and strength weld. At least 6readings shall be taken at each location.

(3) Weld overlay shall be applied circumferentially to the vessel and shall besmooth with no notches or undercuts that would act as stress intensifiers.If necessary, longitudinal application in nozzles up to 8 inch NPS isacceptable. Flaws on the surface of the base metal that would interferewith bonding of the overlay shall be removed by grinding.

(4) Whenever weld deposit overlay is present during vessel seam welding(e.g., longitudinal, circumferential, or nozzle), the overlay shall be cut backin accordance with paragraph 5.4b.(3). Whenever weld deposit overlay ispresent where internal attachments will be welded directly to the basemetal, the overlay shall be cut back in accordance with paragraph 5.4b.(6).


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(5) The weld deposit overlay procedure shall be qualified on base metal of the

same composition as the vessel and thickness of at least one-half of thevessel thickness or 2 inches (50 mm), whichever is less.

(6) Nozzles and manways in alloy lined portions of vessels shall be alloy linedand faced. The nozzle facing shall be made with a minimum of a two layerweld deposit in accordance with Paragraph 5.4b.(4). The surface layershall be weld deposit of the same alloy as the vessel lining and shall be atleast as thick as the vessel lining when properly machined. The first passshall be applied before postweld heat treatment (PWHT). When nozzlesare lined with ferritic Type 405 or 410S stainless steel , the facing welddeposit shall be made with Type 309L welding electrode. For ring jointflanges with an austenitic stainless steel overlay, the second pass shall beapplied after completion of PWHT. The thickness of the first pass and theheat input of the second pass welding procedure shall be such that the basemetal is not affected by the heat and additional PWHT of the base metal isnot required after the second pass.

(7) When austenitic stainless steel weld deposit overlay is used in an elevatedoperating temperature {over 700F (370C)} hydrogen service thefabricator shall demonstrate that their procedures and materials provideimmunity to lining disbonding. Testing shall be per ASTM G 146. As aminimum, the tests shall be representative of the actual operatingconditions (e.g., hydrogen partial pressure, materials and materialthicknesses, temperatures, and heating/cooling rates).

(8) Weld deposit overlay cracks and fissures and volumetric defects thatpenetrate through the overlay or are greater than 1/16 inch (1.6 mm)diameter shall be removed. Repaired areas shall be 100% re-inspected byliquid penetrant.

(9) The weld deposit overlay of each overlayed shell section and head shall beexamined in at least two separate, randomly selected, locations to confirmthe required chemical analysis of the specified overlay material. Eachmanual weld overlay, such as those on girth seams, nozzles, and flangefacings, shall also be examined in the same manner. After machining,analysis at a depth equal to the specified overlay thickness from the surfaceexposed to the process environment shall conform to the chemistryrequirements (e.g., C, Cr, Ni, Nb(Cb), Mo, V, Ti, and Cu as applicable) forthe alloy specified on the UOP Project Specifications. Where weld depositoverlay is applied by more than one welder/welding operator and/orprocedure, examination shall include at least 2 samples of deposits madeby each welder/welding operator for each procedure.


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5.5 Tolerances

a. Vertical vessels shall be checked for plumbness. The outside surface of thecylinder shall not vary from a straight vertical line by more than 1/4 inch (6 mm)in any 20 feet (6000 mm), nor more than 3/4 inch (19 mm) between any twopoints in the total length of the vessel. The vertical reference line shall beperpendicular to the vessels cross section. When the shell thickness is 4 inches(100mm) or more the variation from a straight line shall not exceed 1-1/4 inch(30 mm) between any two points in the total length of the vessel.

b. Horizontal vessels shall comply with the criteria of Paragraph 5.5a. of thisStandard Specification except that the reference line shall be horizontal andperpendicular to the vessels cross section.

c. The maximum offset (misalignment) for longitudinal joints shall be 1/4 inch (6mm) and for circumferential joints 1/2 inch (13 mm).

d. Vessels with internal trays or grids shall not vary more than plus or minus 1/2percent from the nominal diameter specified in the UOP Project Specifications,with a maximum variation in diameter from nominal of 1/2 inch (13 mm).Vessels without trays or grids shall not vary more than plus or minus 1 percentfrom the nominal diameter specified in the UOP Project Specifications, with amaximum variation from the nominal diameter of 1 inch (25 mm).

e. The overall length of the vessel, not including the skirt, shall be within plus or

minus the greater of 1/2 inch (13 mm), or 1/64 inch (0.4 mm) per foot (300 mm)of the length specified in the UOP Project Specifications, up to a maximum ofplus or minus 3/4 inch (19 mm).

f. The length of skirt shall be within plus or minus 1/4 inch (6 mm) of the specifiedlength.

g. Nozzle elevations shall be within plus or minus 3/8 inch (10 mm) andorientations shall be within plus or minus 1/4 inch (6 mm) of the specifiedlocation. The nozzle projection shall be within plus or minus 1/8 inch (3 mm) ofthe specified value.

h. The maximum horizontal or vertical deflection of the machined faces of nozzlesfrom the design plane shall be 1/2 degree or 1/32 inch (0.8 mm), whichever isgreater.

i. Manway elevation, orientation, and projection shall be within plus or minus 1/2inch (13 mm) of the specified values. Tilt shall be within plus or minus 1/4 inch(6 mm) of perpendicular to the nozzle axis.

j. The maximum deviation of internal tray supports from a level (horizontal)reference plane shall be plus or minus 3/8 inch (10 mm).


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k. The maximum variation in spacing between supports for adjacent trays shall

3-12-8 pressure vessels low alloy steel

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