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PTTEP ARTHIT FIELD DEVELOPMENTCENTRAL FACILITIES
PIPING STRESS ANALYSIS SPECIFICATIONA-1-PP-PI-SP-0003
CONTRACT NO . A-TPD 03-0043 This cover page is a record of all revisions of the standard/specification identified above by number and title.
All previous cover pages are hereby superseded and are to be destroyed.
B1 13.08.04 APPROVED FOR DESIGN DR BM ARI BMK SOMCHAIA1 15.07.04 ISSUED FOR APPROVAL DR BM ARI BMKR1 25.06.04 INTER-DICIPLINE CHECK DR BV ARI
Date Purpose of Issue Prepared By
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TABLE OF CONTENTS
1.1 SCOPE 22.0 REFERENCE DOCUMENTS, CODES AND STANDARDS 33.0 OBJECTIVES 54.0 DEFINITION OF CRITICAL STRESS CATEGORIES 6 5.0 STRESS ANALYSIS DESIGN CONSIDERATIONS 86.0 STRESS DOCUMENTATION 107.0 PIPE SUPPORT DESIGN 128.0 NOZZLE ALLOWABLE LOAD CRITERIA (VENDOR SUPPLIED EQUIPMENT,
SKIDS 12 AND PACKAGES) 12 NOZZLE LOADS FOR SIZES ABOVE 30 SHALL BE MUTUALLY AGREED BETWEEN
COMPANY AND VENDOR. 20 APPENDIX- 3 WIND LOADING DATA 21 APPENDIX- 4 TYPICAL RESTRAINT SYMBOLS USED IN STRESS ISOMETRICS22
a) This document defines the method by which piping systems are selected and defined as "Critical" by the Engineering Contractors (KBR) Piping
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Stress Engineer. Critical lines are those to be stress analysed/reviewed by the Piping Stress Engineer.
The term 'piping' referred to in this document is applicable to all of the platform topsides pipe work up to and including the riser ESDV's (Emergency Shutdown Valves) extending up to the hanger flange. The extent of analysis for the topside piping (42 size) riser under PTT scope shall be mutually discussed and agreed.
b) Calculation methods and application of code based procedures for piping stress analysis are defined in this document.
c) This document also defines the permissible values of nozzle loads imposed by piping on connected mechanical equipment, such as exchanger, pressure vessels and rotating equipment as well as equipment skid package tie-in points.
d) This specification is applicable for the topsides pipe work for the Arthit Central Facilities which comprises
i Arthit Central Process Platform (APP)ii Bridge connecting APP and AQPiii Bridge connecting APP and AWP1iv Flare Bridge with Flare Tower connecting APP to the Flare Tripod
All piping calculations, dimensions and weights shall be in Systeme Internationale ( SI ) units.
The following definitions shall apply to this specification:
Company PTTEP - Petroleum Authority of Thailand Exploration and Production, Public Company Limited.
Engineering Contractor KBR - Kellogg Brown & Root Asia Pacific Pte Ltd
Stress Engineer - Engineering Contractors Piping Stress Engineer
2.0 REFERENCE DOCUMENTS, CODES AND STANDARDS
2.1 Project Specifications
2.1.1 A-1-PP-PI-SP-0004 Specification for Spring Support
2.1.2 A-1-PP-PI-SP-0007 Insulation Specification
2.1.3 A-1-PP-PI-SD-0006 Pipe Support Standard
2.1.4 A-1-PP-PI-SP-0005 Pipe Support Design Specification
2.1.5 A-1-PP-PI-LL-0001 Critical Line List
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2.2 Reference Company Documents
2.2.1 AGS-03 Unfired Pressure Vessels 2.2.2 AGS-05 Steel Piping Design, Fabrication, and Installation
2.2.3 AGS-08 Piping Materials
2.2.4 AGS-18 Site Condition and Climate
2.2.5 AGS-20 Shell and Tube Heat Exchanger
2.2.6 AGS-21 Air Cooled Heat Exchanger 2.3 Codes and Standards Design and analysis of the piping shall be in accordance with following codes.
ASME B31.3 Process Piping
ASME B31.4 Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids
ASME B31.8 Gas Transmission and Distribution Piping Systems
API RP 14E Recommended Practice for Design and Installation of Offshore Production Platform Piping Systems
In addition to ASME B31.3, B31.4, B31.8 & API RP 14E and its sub-references, following codes shall also govern the design and installation of some parts of a piping system and the connected equipment.
ASME B16.5 Pipe Flanges and Flanged Fittings
ASME B16.47 Large Diameter Steel Flanges
API RP 520 Sizing, Selection and Installation of Pressure Relieving Devices in Refineries Part II - Installation
API RP 521 Guide for Pressure Relieving and Depressurising Systems
API RP 686 Recommended Practices for Machinery Installation and Installation Design (Chapter 6 Piping)
API 610 Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries
API 617 Axial and Centrifugal Compressors and Expander Compressors for Petroleum, Chemical and Gas Industry Services
API 618 Reciprocating Compressors for Petroleum, Chemical and Gas Industry Services.
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API 650 Welded Steel Tanks for Oil Storage
API 660 Shell-and-Tube Heat Exchangers for General refinery Services
API 661 Air Cooled Heat Exchangers for General Refinery Services
API 662 Plate Heat Exchangers for General Refinery Services
UKOOA Specification and Recommended practice for the use of GRP Piping Offshore
ISO 14692 Specification and Recommended practice for the use of GRE Piping Piping in the Petroleum or Natural Gas Industries
BS7159 Design and construction of glass reinforced plastics GRP) piping systems for individual plants or sites
BS CP3 Basic data for the design of buildings Chapter V. Loading Part 2. Wind loads
NEMA SM23 Steam Turbines for Mechanical Drive Service.
WRC-107 Local Stresses in Spherical and Cylindrical Shells due to External Loadings
WRC-297 Local Stresses in Cylindrical Shells due to External Loadings on Nozzles Supplement to WRC 107
The objectives for performing stress analysis of piping systems shall include the following.
a) To keep the stresses in the pipes and fittings within the code allowable levels.
b) To keep the nozzle loadings on the attached equipment within allowable limits of applicable specifications or recognised standards (NEMA SM23, API 610, API 661, etc.)
c) To minimise vibration of the reciprocating compressor associated piping.
d) To calculate the design loads for sizing of in-line restraints such as U-bolt, Shoe, Clamp, Trunnion, Guide, Stop, etc., sizing of support frames and selection of spring hangers.
e) To determine the piping displacements for interference check and prevent excessive sag in piping spans.
f) To check the leakage at the flange joints.
g) To prevent unintentional disengagement of piping from its supports.
h) To help optimize the piping design.
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4.0 DEFINITION OF CRITICAL STRESS CATEGORIES
4.1.1 Non-Critical Lines
All metallic, ferrous and non-ferrous lines 2" NB and smaller are deemed non-critical and do not require a formal pipe stress analysis calculation unless specified otherwise. Lines larger than 2 NB that do not fall under any of the criticality criteria listed below shall also be treated as non-critical lines. Some non-critical lines may require special attention, e.g., small branches subject to large displacements and blow down lines. However these lines shall be reviewed / checked for support detail by the stress engineer.
4.1.2 Critical Line List
Upon receipt of Piping and Instrument Diagrams (P & ID's), Line List and Piping Specifications, the Stress Engineer shall identify the critical lines and prepare a Critical Line List. These lines require formal pipe stress analysis calculations
4.1.3 Critical line selection
A line is defined as critical if it falls into any of the following criticality criteria.
4.2 Criticality Criteria:
a) 18" NB and larger
b) 4" NB and larger at 95C and above
c) 3" NB and smaller at 150C and above
d) 3" NB and larger at -28C and below
e) Alloy, stainless steel and non-ferrous piping 6" NB and larger at 70C and above
f) Process lines 4 and above connected to Rotating machinery such as pumps, centrifugal compressors, gas turbines, fans and blowers
g) All process lines connected to Reciprocating compressors and pumps
h) All lines process connected to Special items of equipment, which have low allowable loads, specified by the equipment Vendor
i) All process lines connected to Air-cooled exchangers (fin fans)
j) All process lines connected to Shell and Tube Heat Exchangers, Plate Heat Exchangers, Printed Circuit Heat Exchangers and Waste heat Recovery Units (WHRU)
k) Lines subjected to unbalanced surge forces
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l) Lines containing quick acting pressure relieving devices, e.g., relief valves and bursting discs and blow down valves
m) Thick wall pipe, i.e., schedule 160 and above for pipe size 4 & above only
n) Thin wall, large bore pipe, i.e., schedule 10 and below and 18" and above.
o) Lines containing expansion devices such as bellows, (only if applicable)
p) Gas or vapour lines, including the flare system, in which liquid slugs may form and cause high impact loads at valves, bends, tees or vessels.
q) Lines liable to extreme terminal and support deflections and rotations caused by deck movement
r) Vacuum and externally pressurised lines , including those liable to transient external pressure conditions.
s) Liquid blow down piping, not including drain lines.
t) Lines which the stress engineer considers require special attention but which are not critical by the above definitions.
u) Riser lines and process lines connected to Launchers / Receivers
v) All lines running on the platforms linking bridges
4.3 Stress analysis method
CAESAR II, Verson-4.5 computer program shall be used for stress analysis calculations.
4.4 Piping Studies
The Stress engineer shall review and comment on all piping studies pertaining to critical lines. Preliminary pipe support locations shall be identified by piping layout/support section based on good engineering practice considerations, such as span, structure availability and grouping of supports. However the stress engineer shall review and identify, based on the analysis, the final location as well as the type of restraints, such as anchor, directional restraints and springs.
Locations of fixed and sliding ends for horizontal vessels and equipment shall be defined by Stress engineer in consultation with other applicable disciplines, Mechanical, Structural etc., as appropriate.
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5.0 STRESS ANALYSIS DESIGN CONSIDERATIONS
5.1 Analysis shall be carried out at the design ( max and/or min) temperatures and coincident Design pressure conditions of the selected lines. Where this will lead to an over-conservative design, operating conditions (operating temperature and pressure) of the system shall be used in the analysis. The ambient temperature shall be 36C maximum and 22C minimum as per section 4.0 of AGS-18 and solar radiation metal temperature shall be 80C.
5.2 Support friction shall be considered for the analysis, and the coefficient of friction shall be taken as 0.3, for steel to steel surface contact. For supports in the vicinity of nozzle loads sensitive equipment such as pumps and compressors, a low friction coefficient of 0.1 may be considered if required and the sliding unit (PTFE) to achieve the low friction shall be provided at the support base. Friction factor shall be suitably considered for the combination of sliding surfaces.
5.3 Equipment nozzle shall be modelled as anchor with initial thermal movements. If the calculated reaction loads exceed the allowable values for the nozzles, the nozzles shall be modelled as flexible nozzles
5.4 Piping to and from relief devices shall be designed and/or supported/braced to ensure that exhaust reaction loads, or moments, do not exceed that permitted by the relief valve manufacturer, the equipment manufacturer or the piping code. Bracing of the inlet line to the outlet line is not permissible.
5.5 Stress analysis of piping systems connected to rotating equipment such as pumps shall consider all probable scenarios of operation such as operation and standby etc. Future piping connections, wherever possible, shall also be included in the analysis. Large Pumps require particular attention with regard to nozzle loads. Requirements of large pumps are generally similar to those for compressors.
5.6 For compressor piping, design temperatures shall generally be used to establish pipe thermal expansion for nozzle load purposes. Values should be discussed and agreed with the Process dept.
Pipe routing should allow for restraints to be located in line with the machine axes, to effectively cancel expansion forces on the nozzle. Adjustable stops and guides must be provided in both horizontal planes to assist with alignment. Weight supports other than springs shall similarly be adjustable.
Spring supports if required shall be constant force type or long range variable and to be very close to the machine, to allow accurate pipe positioning during the alignment process. A piping system entirely supported on springs shall be avoided.
The weight run on which spring design is based shall be made with the compressor nozzle disconnected vertically in order to transfer minimum loads to the nozzle.
Restraint with guide and stop local to the anti-surge or recycle valve shall be added to avoid vibration due to gas turbulence.
Pipe support designs shall be reviewed by Engineering Contractors structural engineer to ensure that stress requirements have been complied with.
PTTEP Arthit Field Development Doc. No. A-1-PP-PI-SP-0003 Rev. B1Central FacilitiesPiping Stress Analysis Specification Page 9 of 23 5.7 Bridge piping
Three bridges are linked to Arthit Central Process Platform APP. Location of the bridges fixed and sliding ends shall be confirmed and bridge piping configurations to be reviewed to assess the requirement of expansion loops. Also settlements of platforms and longitudinal & lateral movements shall be considered for bridge piping stress analysis when connected to the existing platform piping. The three bridges are:
a) Bridge connecting APP and AQPb) Bridge connecting APP and AWP1c) Flare Bridge with Flare Tower connecting APP to the Flare Tripod
5.8 Output shall be scrutinised for
a) Stress check for code compliance in sustained, expansion and occasional cases.b) Load check for nozzle allowable values for connected equipment specified in section 9.0 -Nozzle allowable load criteriac) Support reaction loads for pipe supports design.d) Excessive piping displacements for interference check and sagging.
5.9 Load Cases
a) Operating case: This shall include effects of pressure, temperature, pipe dead weight, insulation weight, weight of the contents and other externally imposed displacement such as nozzle displacements etc. This load case is required to be performed to establish that the operating condition loads on the equipment nozzle and pipe supports are within safe limits.
b) Sustained case: This shall include only the effects of pressure, pipe dead weight, insulation weight and weight of contents. This case is required to be done mainly to check if the code compliance requirements of sustained stresses are satisfied by the piping system.
c) Expansion case: This shall include effects of temperature and externally imposed displacements such as nozzle displacements etc. This case is for verifying the code compliance requirements of expansion stresses.
d) Occasional case: This shall include effects of wind, wave load (if any), and pressure relief valve reaction forces, each should be analysed independently. As per provision of ASME B 31.3, no two occasional load cases need to be considered simultaneously for compliance requirements. This case is required for getting additional loads transferred by occasional forces to structure at pipe supports, guides, nozzles, anchor locations and also for verifying code compliance requirements of occasional stresses.
For wind loading data refer Appendix-3.
e) Slug load case: Liquid slugs entrained in flowing gas exert a force on any change of direction or change in pipe size. The velocity and specific gravity values have a profound effect upon calculated loads and realistic data must be agreed with the Process Dept. Forces acting at a change of direction may be evaluated by consideration of momentum change or centrifugal force. A dynamic amplification factor of 2.0 (max) shall be considered
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unless specified otherwise which is dependent on velocity and piping component type. This case is required to be done mainly to design the pipe support structure for slug load and to check the stress in the piping system due to slug load.
f) Hydrostatic test case: This is to verify the stress occurring during testing as well as to establish the maximum loads that need to be supported by the designed pipe support/structure.
g) Surge case analysis: Surge analysis as applicable and as required will be carried out by the third party agency. The unbalanced forces as provided by the surge specialist will be used in the CAESAR analysis to calculate the stress and support loads.
h) Blast load case: Analysis shall be carried out as applicable. The drag forces as provided by the Safety group will be used in the CAESAR analysis to asses the stress and support loads.
Transportation Case: Separate transportation analyses shall be carried out taking in to account the effect of barge motion (acceleration) and the deck new set of deflections. Based on the results, recommendations will be provided for piping disconnections from the equipment nozzles to avoid any overloading.
Appendix-1 shows load cases to be built up in CAESAR.
6.0 STRESS DOCUMENTATION
6.1 Stress calculation (CAESAR file) Numbering
Stress calculation input files should be numbered as follows:
Example:ACF1101NAD1WhereACF Arthit Central Facilities
The first digit of the 4 digit number shown in box is allocated as follows.
1 Arthit Central Process Platform (APP) 2 Bride connecting APP and AQP 3 Bridge connecting APP and AWP1 4 Flare Bridge with Flare Tower connecting APP to the Flare Tripod 5 Arthit living Quarters Platform (AQP)
The last three digits are allocated as follows:
000 to 099 Separation Piping including incoming/outgoing Riser Lines, Headers and Produced Water Piping
100 to 199 Mercury Removal System Piping
200 to 299 Feed Gas Compression Piping
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400 to 499 NGL Extraction Piping
500 to 599 Sales Gas Compression Piping
600 to 699 Condensate Stabilization Piping
700 to 799 VRU Compression Piping 800 to 899 Fire Water Piping 900 to 999 Utility and other Piping
NA,NB, etc., Normal case Calculation sequence
BA,BB, etc., Blast case Calculation sequence
TA,TB, etc., Transportation case Calculation sequence
R1, D1, D2 etc., Revision number
6.1 Preparation of Stress Isometrics
Stress isometrics will be extracted from PDMS and they shall be numbered as follows.
The four digit number shown as a last entry in the above numbering shall be same as the four digit number used for the stress calculation file.
All restraints acting on the piping shall be clearly indicated using standard legends found in Appendix-4.
Sufficient nodes must be shown to allow a third party to navigate around the system when reading the drawing in conjunction with a CAESAR II input listing.
6.2 Master Stress Isometrics
A master file of stress isometrics shall be maintained and agreed changes signed and dated.
6.3 Input file Handling Input files shall be electronically archived on completion of each calculation. Only the files with a _A and _J trailer need to be kept and backed up on the O drive. A record of files archived shall be maintained.
6.4 Stress Analysis Report
The Stress Analysis Report will be compiled after all Fabrication isometrics for the stress critical lines have been issued. It is intended to provide evidence of all work completed by stress engineer in selection, analysis and approval of critical lines.
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The preferred format of stress analysis report is as follows:
Contents, Summary and calculations, system and analysis description, Critical line list and stress isometric index, stress iso, data and calculations, General and calculations.
The preferred format is to exclude computer output from CAESAR II and to supply with disc copies of all input files from which output can be generated if required.
7.0 PIPE SUPPORT DESIGN
Stress engineer shall review in-line support details. The review must ensure that the supports and restraints are fit for purpose, for example whether restrained along the correct axes, support requirement for concentrated loads
Standard support details shall be used wherever possible to suit the deck steel work.
Pipe support with spring hanger shall only be used where all other possible design solutions have been exhausted.
Spring design data sheets shall be completed by the stress engineer and the necessary input such as elevation details shall be provided by the pipe supports group.
8.0 NOZZLE ALLOWABLE LOAD CRITERIA (Vendor supplied Equipment, Skids and Packages)
8.0.1 The allowable forces and moments stated in this specification apply directly to steel equipment and at the tie-in interfacing nozzle flange face whereas for Pressure vessels and Shell & Tube Heat Exchangers, the loads are applicable at nozzle/shell intersection .
8.0.2 For Titanium equipment, the allowable loads shall be 70% of the load values given in Appendix-2 or as agreed with the vendor.
8.0.3 For Cupro-Nickel equipment, the allowable loads shall be 50% of the load values given in Appendix-2 or as agreed with the vendor.
8.0.4 For other materials including GRP, the Vendor shall provide an appropriate set of calculations for review and approval.
8.0.5 A statement of compliance, with this Specification, shall be provided by the Vendor.
8.0.6 The piping loads contained in this specification apply to design conditions only. If the nozzle design loads exceed the allowable limit, when the piping is designed for occasional load cases, such as, wind, wave, PSV forces and occasional slugging, these loads will be submitted for Vendors approval during the detail design phase.
8.1 Centrifugal Pumps
The allowable forces and moments on pump nozzles due to piping reactions shall be two times the values given in table-4 of API 610, 9th Edition for nozzle sizes 16 and below. This also applies to Vertical In-line pumps and Horizontal/Vertical Suspended pumps.
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Nozzle loads on Horizontal End Suction Centrifugal Pumps and Vertical In-Line Centrifugal Pumps in accordance with ASME B73.1 and B73.2 shall also be two times the values given in table-4 of API 610, 9th Edition.
Should there be a requirement for increased nozzle allowable forces or moments in any one or more directions at the detailed engineering stage, the same shall be mutually discussed and agreed between the Vendor and Company.
For pump nozzle sizes above 16, Company will provide the forces and moments at the pump nozzles based on the stress analysis of the system for review and acceptance by the vendor.
8.2 Centrifugal Compressors & Turbo Expander Compressors
The loads on Centrifugal Compressor and Turbo Expander Compressor nozzles shall be in accordance with NEMA SM23 Section 8.4.6 formulae; however the constants in formulae shall be increased by a minimum factor of 4
Should there be a requirement for increased nozzle allowable forces or moments in any one or more directions at the detailed engineering stage, the same shall be mutually discussed and agreed between the Vendor and Company. Net resultants of combined forces and moments shall be resolved at the suction (larger) nozzle in the case of a two-nozzle machine. The equivalent nozzle diameter Dc shall be based on the nominal nozzle outside diameters.
8.3 VRU System Reciprocating Compressor Package
Vendor shall inform the desired minimum mechanical natural frequency to be established for the entire VRU piping system starting from suction scrubber inlet lines up to the discharge scrubber outlet lines.
The piping within VRU compressor package shall be supported and guided, as
necessary, and the interface tie-in points shall be anchored by the vendor such that the interface nozzle shall be designed to satisfy the Forces and Moments stated in Appendix-2.
For some reasons, if it is not possible for vendor to provide anchor at the interface tie-in points, then the vendor shall provide stiffness values and thermal movements at the compressor nozzles in all degrees of freedom (3 translations and 3 rotations). Engineering Contractor will provide loads (forces and moments) imposed by piping at the compressor nozzles based on the stress analysis of the complete system for review and acceptance by the vendor.
8.4 Pressure Vessels, Columns, Filters and Pig Launchers / Receivers
8.4.1 External loads applied to Pressure vessels and columns nozzles shall normally be limited to the values given in Appendix-2 of Arthit General Specification AGS-03 (Unfired Pressure Vessels)
8.4.2 In the event that a component force or moment due to piping reactions exceeds therespective allowable but the resultant remains within the resultant allowable,
WRC107 / WRC297 calculation may be performed by the Company to accept the loads. In case the WRC calculation fails, Company will modify the piping and/or restraints to limit the loads within the values given appendix-2 of AGS-03. If this is
PTTEP Arthit Field Development Doc. No. A-1-PP-PI-SP-0003 Rev. B1Central FacilitiesPiping Stress Analysis Specification Page 14 of 23 not achievable by the Company, the loads will be provided to the vendor. Vendor shall re-analyse the vessel for new loads to verify and ensure that all stresses are still within the allowable limits with suitable modification if any on the vessel.
8.4.3 If component and resultant exceed the allowable loads, piping and / or restraints will be modified to comply with values given in Appendix-2 of AGS-03. If this proves to be impractical, Company will provide the loads for review and acceptance by the vendor for suitable modification if any on the vessel.
8.4.4 The locations and loading for pipe support clips on the vessel and/or service platform will be furnished separately during the detailed engineering stage which shall be verified by the Vendor for the stresses and other aspects of vessel and service platform design.
8.5 Shell & Tube Heat Exchangers, Double Pipe Type Heat Exchangers, Plate Type Heat Exchangers & Printed Circuit Heat Exchanger
External loads applied to nozzles of shell & tube heat exchangers, Double pipe type heat exchangers, Plate type heat exchangers and Printed circuit heat exchangers shall normally be limited to the values given in Appendix-2. External Forces and Moments given in Appendix-2 are to be applied at nozzle / shell intersection simultaneously. Sections 8.4.2, 8.4.3 & 8.4.4 are applicable here also.
8.6 Air Cooled Heat Exchangers
Allowable loads shall be three times the values given in API 661 Table 4. Should there be a requirement for increased nozzle allowable forces and moments in any one or more directions at the detailed engineering stage, the same shall be mutually discussed and agreed between the vendor and Company.
If pipe support clips are required on the cooler service platforms, locations and
loadings for the clips will be furnished separately during the detailed engineering stage which shall be verified by the Vendor for the stresses and other aspects of platform design.
Unless agreed with Company, the allowable nozzle loads for flat sided storage tanks are as tabulated below.
Table-A ( Metric Units )
Direct Loads (N) Moment Loads (N-m)
F Axial F Shear M Torsion M Bending1 750 750 150 150
2 750 750 150 1503 1500 2000 750 4504 2000 3000 1400 7506 3000 5000 3000 20008 3500 6000 4500 3000
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1) All loads stated above act at the tank plate / nozzle intersection and are to be assumed to act simultaneously.
2) The Vendor shall provide sufficient local reinforcement to ensure that the stress due to pressure head, radial load and applied moment does not exceed 1.5 times the allowable design stress for the plate.
3) For nozzles exceeding 8 N.B, allowable loads shall be agreed with the Company.
8.8 Waste Heat Recovery Unit
Based on the analysis, Engineering Contractor will provide loads (forces and moments) imposed by piping at Heating Medium inlet and outlet nozzles of Waste Heat Recovery Unit (WHRU) for review and acceptance by the Vendor.
8.9 Packaged Units
8.9.1 Package unit Vendor shall furnish the list of lines considered for stress analysis for Companys review. Stress analysis for Package unit piping carried out by vendor shall be as per this specification as a minimum. 8.9.2 When the piping is connected to equipment other than that specified in this Specification, the loading listed in Appendix-2 shall be used.
8.9.3 The Vendor shall anchor all package piping at the skid edge. Where this proves impractical, the Vendor shall advise the Company no later than six weeks after award of the contract. The piping within the package shall be supported and guided, as necessary, by the Vendor such that the interface nozzle shall satisfy the Forces and Moments stated in Attachement-2. The Vendor shall provide isometric drawings showing all pipe support restraints.
8.9.4 For terminations anchored at a skid edge, the allowable external loading (from piping outside the package) will correspond to the Forces & Moments stated in Appendix-2. Tie-in anchor, at the Vendor/Company interface, shall be capable of withstanding two times the values as per Appendix-2.
8.9.5 Should there be a requirement for increased allowable forces or moments in any one or more directions at the detailed engineering stage, the same shall be mutually discussed and agreed between the Package Unit Vendor and Company.
8.10 Tie-ins between Topsides and Risers
For riser connected topsides piping, Hanger Flange shall be treated as an anchor for carrying out topsides piping stress analysis. The forces and moments due to topsides piping shall be taken into account for hanger flange design.
8.11 Flange joints
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Supports are to be provided close of flange joints, where heavy concentrated loads occur. A review will be done by the stress engineer for these types of supports.
Pressure design of flanges shall generally be in accordance with section 304.5 of ASME B31.3. Operating pressure shall be considered for the purpose of flange leak calculation.
Piping stress analysis programme CAESAR II shall be used for checking the flange leakage.
8.12 Vendor Drawings and Data
The stress section shall review and comment on all Vendor drawings, such as, equipment and vessels, pertaining to connected stress critical piping. Review shall include interface tie-in connection drawings and details for Package/skid units, pertaining to stress critical lines.
APPENDIX-1 CAESAR LOAD CASES
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NORMAL CASESASME B31.3 Stresses, Nozzle Loads , Restraint Loads & Hydro-test Restraint loads
Simple System1 W+D4+T1+P1 (OPE)2 W+P1 (SUS) B31.3 Stresses3 WIN1 (OPE)4 WIN2 (OPE)5 WW+HP (HYD) Hydro-test Loads6 L2+L3 (OCC)8 L2+L4 (OCC)9 L1+L3 (OPE)10 L1-L3 (OPE) 11 L1+L4 (OPE) 12 L1-L4 (OPE) 13 L1-L2 (EXP) B31.3 Stresses
System with added PSV Forces1 W+D4+T1+P1+F1 (OPE)2 W+P1+F1 (OPE)3 W+P1 (SUS) B31.3 Stresses4 WIN1 (OPE)5 WIN2 (OPE)6 WW+HP (HYD) Hydro-test Loads7 L2+L4 (OCC)9 L2+L5 (OCC)10 L1+L4 (OPE)11 L1-L4 (OPE)12 L1+L5 (OPE)13 L1-L5 (OPE)14 L1-L2 (EXP) B31.3 Stresses
System with Spring Hangers1 W (HGR)2 W+D4+T1+P1 (HGR)3 W+D4+T1+P1+H (OPE)4 W+P1+H (SUS) B31.3 Stresses5 WIN1 (OPE)6 WIN2 (OPE)7 WW+HP (HYD) Hydro-test Loads8 L4+L5 (OCC)9 L4+L6 (OCC)10 L3+L5 (OPE)11 L3-L5 (OPE)12 L3+L6 (OPE)13 L3-L6 (OPE)14 L3-L4 (EXP) B31.3 StressesHydro-test load case shall be run separately with Springs replaced byRigid hangers.
BLAST CASE Stresses & Restraint Loads1 W+D4+T1+P1 (OPE)2 W+P1 (SUS)3 BLAST X (OCC)4 BLAST Y (OCC)5 BLAST Z (OCC)6 L1+L3 (OPE)7 L1-L3 (OPE)8 L1+L4 (OPE)9 L1-L4 (OPE)10 L1+L5 (OPE)11 L1-L5 (OPE)12 L2+L3 (OCC)13 L2-L3 (OCC)14 L2+L4 (OCC)15 L2-L4 (OCC)16 L2+L5 (OCC)17 L2-L5 (OCC)
TRANSPORTATION CASE B31.3 Stresses, Nozzle & Restraint LoadsWNC+D1+D2+D3+U1+U2+U3(SUS)
SLUG CASE This case is similar to Normal case with added forces. The added forces are Slug forces at pipe elbows.
SURGE CASE This case is also similar to Normal case with added forces. The added forces are Surge forces at pipe elbows. If the system has to be designed for the effect of surge at one elbow at a time, then as many number of cases as the number of elbows in the system have to be analysed to determine the worst loads.
W - Pipe Weight, Insulation Wt, Fluid Wt, Rigid WtWW - Pipe Weight, Insulation Wt, Water-filled Wt, Rigid WtWNC - Pipe Weight, Insulation Wt, Rigid WtP1 - Design or Operating Press.HP - Hydrostatic Test PressureT1 - Design or Operating Temp.D1,D2 - Deck deflections during & D3 transportationD4 - Anchor Thermal Movement F1 - Applied Forces or MomentsH - Hanger LoadWIN1 - X direction Wind PressureWIN2 - Z direction Wind Pressure BLAST - Blast Forces in X,Y,Z - X,Y,Z Directions U1,U2 - Acceleration during & U3 transportation
OPE - Operating (No code stress check)SUS - Sustained caseOCC - Occasional caseEXP - Expansion caseHYD - Hydro-test caseHGR - Hanger Load case
B31.3 StressesB31.3 Stresses
Stress Check,Allowable = Yield
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APPENDIX-2 EXTERNAL FORCES AND MOMENTS ON NOZZLES
Forces, N Moment, N-m
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APPENDIX-2 EXTERNAL FORCES AND MOMENTS ON NOZZLES (Contd)
Forces, N Moment, N-m
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APPENDIX-2 EXTERNAL FORCES AND MOMENTS ON NOZZLES (Contd)
Forces, N Moment, N-m
Nozzle Loads for sizes above 30 shall be mutually agreed between Company and Vendor.
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APPENDIX- 3 WIND LOADING DATA As per Arthit General Specification AGS-18 (Site Conditions and Climate) the 100 year return Wind speed (3 second Gust) at 10m above LAT (Lowest Astronomical Tide) is 57m/sec.The corresponding wind speed at other elevations (Z) are estimated using the formula VZ=V10(Z/10)0.12 Wind load is applied as uniform force along the pipeWind force per unit length F = CfqD N/mmWhereD = Outside diameter of the pipe, mmq = Dynamic pressure of the wind = V/2 , N/mCf = Shape factor or Effective force co-efficientV = Wind Speed, m/sec = Density of air = P/RT, Kg/m P = Atmospheric pressure = 101396.16 N/mT = Average air temperature = 29C as per Table 4.1 of AGS-18 R = Gas constant for air = 287.1387 N-m/Kg-KAir Density at 29C = 101396.16/[287.1387x(29+273)] = 1.1693 Kg/ m
Wind Profile based on 100 year return interval, 3 second Gust
N/m5 52.5 1611.4
10 57.0 1899.515 59.8 2090.7 20 61.9 2240.125 63.6 2364.930 65.0 2470.135 66.2 2562.240 67.3 2648.045 68.3 2727.350 69.1 2791.6
As per BS CP3, Chapter V, Part 2, values of shape factor Cf for pipe sections are as follows.
Flow Regime DV Value Cf
Subcritical flow DV < 6 m/sec 1.2
Supercritical flow6 DV < 12 m/sec 0.612 DV < 33 m/sec 0.7
DV 33m/sec 0.8
The above wind profile and shape factor values shall be used in CAESAR II Pipe Stress analysis. The Y co-ordinate to be keyed-in for the starting node in CAESAR II input shall be the elevation in metres of the corresponding point in PDMS stress isometrics.
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APPENDIX- 4 TYPICAL RESTRAINT SYMBOLS USED IN STRESS ISOMETRICS
Hanger Support Rest Support Rest Support with Hold Down
Hanger Support with Pipe Guide
Rest Support with Pipe Guide
Rest support with Hold Down & Pipe Guide
Hanger Support with Pipe Axial Stop
Rest Support with Pipe Axial Stop
Rest Support with Hold Down & Pipe Axial Stop
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APPENDIX- 4 (Contd.)TYPICAL RESTRAINT SYMBOLS USED IN STRESS ISOMETRICS
Pipe Guide & Axial Stop Rest support with Pipe Guide & Axial Stop
Rest support with Hold Down , Pipe Guide & Axial Stop
Spring Support (Pedestal type)
Spring Support with Pipe Guide
Spring SupportWith Axial Stop
Spring Support With Pipe Guide &Axial
Spring hanger support,
Spring hanger support withPipe Guide
Spring hanger support withAxial Stop
Spring hanger support with Pipe
Guide & Axial Stop
1.1 Scope2.0 REFERENCE DOCUMENTS, CODES AND STANDARDS3.0 OBJECTIVES4.0 DEFINITION OF CRITICAL STRESS CATEGORIES5.0 STRESS ANALYSIS DESIGN CONSIDERATIONS5.9 Load Cases
6.0 STRESS DOCUMENTATION7.0 PIPE SUPPORT DESIGN8.0 NOZZLE ALLOWABLE LOAD CRITERIA (Vendor supplied Equipment, Skids and Packages)Nozzle Loads for sizes above 30 shall be mutually agreed between Company and Vendor.APPENDIX- 3 WIND LOADING DATAAPPENDIX- 4 TYPICAL RESTRAINT SYMBOLS USED IN STRESS ISOMETRICS