This specification discusses pressure vessels' Inspection, Testing, Painting, Marking, Preparation for Shipping and Storage in compliance with the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.
This specification in combination with general pressure vessel requirements including engineering design and fabrication will define the minimum acceptable requirements of unfired pressure vessels suitable for installation in energy industry.
1.0 Inspection and Testing
Buyer reserves the right to inspect, or for an authorized representative to inspect, vessels at any time during fabrication and to have access to all test records and results.
Supplier should afford Buyer, free of cost, all necessary and reasonable information and use of facilities needed for determining that vessels are being furnished in accordance with the Technical Requirements and vessel data sheets.
Buyer inspection should not relieve Supplier of responsibility for all examinations necessary to assure compliance with the ASME Code and the requirements of this specification and the vessel data sheet.
Prior to the final inspection, all slag, loose scale, dirt, grit, weld splatter, paint, oil, test medium and other foreign matter should be removed from inside and outside the vessel.
For vessels in cyclic service, for which attachment welds to pressure parts have been ground to a smooth radius, the ground welds should be checked by magnetic particle or dye Penetrant examination.
1.2 Non Destructive Examination
Supplier should provide ultrasonic or magnetic particle inspection of all welds utilizing the Flux Core Arc Welding (FCAW) process.
For nozzle attachment welds using FCAW, 100% ultrasonic inspection is required.
Note: Supplemental inspection requirements may be adopted to monitor in-service H2S-induced cracking.
Ultrasonic inspection in accordance with ASME Code, Appendix 12 should be required for all Code Category C and D welds.
1.3 Radiographic Inspection
As a minimum, all butt welds (including butt welds for flange-to-pipe nozzles and nozzles constructed of rolled plate) should be spot radiographed in accordance with ASME Code.
- One radiograph should be taken showing not less than 14" (350 mm) of weld for each longitudinal and each circumferential joint in the shell and heads.
- One spot radiograph (14") (350 mm) should be taken of each butt weld in the skirt of a vertical vessel.
When 100% radiography is specified, all butt welds should be included.
- Spot radiography per first bullet above is also mandatory for all Category B welds, including nozzles, only when full radiography is required
- Category C and D welds should receive the following inspections:
- Backgouged surfaces of all Category C and D welds should be liquid penetrant or magnetic particle tested per Appendix 8 or Appendix 6 of the ASME Code, as applicable.
- All surfaces of completed Category C and D welds should be magnetic particle inspected per Appendix 6 of ASME Code.
- Unless otherwise specified, NDE in above items will be randomly inspected by a Buyer inspector or representative.
- When specified in the vessel data sheet as an alternative to previous bullet point, ultrasonic testing (UT) is required for Category C and D welds in accordance with Code Appendix 12. This option is required only when full radiography is mandated in the vessel data sheet or project requirements.
When full (100%) radiography is specified for solely Code Category A weld joints, spot radiography should be required for all Code Category B welds, including nozzles.
Welds subjected to forming operations, as might occur in a welded head, should be fully (100%) radiographed after forming, but before attachment to the vessel.
Buyer should be notified five (5) working days in advance of final spot radiography, so that Buyer may designate the locations of the random radiographs.
- For any rejectable weld defects that, in the opinion of Buyer, do not appear to be random in nature, the entire length of that weld should be radiographed.
- Should additional repairs be required, then Supplier should repair all defects in accordance with ASME Code, and Supplier should bear all costs for the additional radiographs and repairs.
- Should repairs not be required, Buyer will reimburse Supplier for the costs of the additional radiographs.
- Any vessel that becomes fully (100%) radiographed should be given ASME Code status and stamped as a fully radiographed vessel.
For carbon steel vessels, radiographs should not be taken within 24 hours of completion of the weld being examined.
Radiographic film should be retained by Supplier for at least a year after the date that the Authorized Inspector approves the Manufacturer's Code Data Report.
All welds in piping outside the limits of the ASME Code should be inspected radiographically and interpreted in accordance with ASME B31.3.
Piping requiring stress relieving should be radiographed before and after stress relieving.
1.4 Hydrostatic Pressure Testing
After completion of all fabrication, welding, visual inspection, NDE, radiography, stress relieving and telltale-hole air tests, Supplier should perform a hydrostatic test in accordance with the ASME Code.
- Hydrostatic tests should be performed in the presence of, and with the approval of, Supplier's Authorized Inspector and/or Buyer.
- Vessels should not have been previously hydrotested by Supplier without Buyer authorization.
- Hydrostatic testing of piping outside the limits of the ASME Code should be as prescribed in ASME B31.3.
Supplier should furnish all test facilities, equipment and materials, including chart recorder, gauges, blinds, studs, nuts, gaskets, etc. necessary for the test.
The vessel should be cleaned internally and externally of all dirt, debris, weld slag, weld spatter, etc. before hydrostatic testing.
The hydrostatic test should be performed with the "in service" type of gaskets, and should not utilize any gasket sealing compounds.
Vessels should not have been primed, painted, or internally coated prior to hydrostatic testing.
Supplier should provide ten (10) days advance notification so that the hydrostatic test may be witnessed by Buyer.
Fresh potable water should be utilized for hydrostatic testing. The minimum water and metal temperature for the test should be 600F (150C) above MDMT at MAWP, whichever is warmer.
Hydrostatic Test Pressure should be determined as follows:
- The hydrostatic test pressure should be the pressure calculated to stress the full thickness, including corrosion allowance and cladding, if any, of the strongest Category A weld to a minimum of the appropriate Code test factor (i.e., 1.3 for Division 1 vessels or 1.25 for Division 2 vessels) times the allowable stress for the material at the test temperature.
- This pressure is based on the Code test factor times the Maximum Allowable Pressure New and Cold (MAP).
- No component of the vessel should be stressed above 90% of its specified minimum yield strength.
- If the hydrostatic test pressure so calculated will stress components of the vessel above 90% of the specified minimum yield strength, the test pressure should be reduced by the least amount necessary to avoid overstressing weaker components.
The minimum test time should be one (1) hour after stabilization of pressure and temperature.
- Test pressure and temperature should be chart recorded.
- Ambient air temperature should be recorded at the start and end of testing.
After the final hydrostatic test, the vessel should be drained completely and dried thoroughly.
- Draining and drying should be completed within one week of filling the vessel with hydrostatic test water.
- If the vessel cannot be visually inspected to ensure complete drying, the Supplier should use a dehumidified air dryer to show that the outlet relative humidity is the same as the inlet relative humidity.
Horizontal vessels should be hydrostatically tested with the permanent support saddles. Additional temporary supports should not be allowed.
Vertical vessels should be properly supported if hydrostatically tested in the horizontal position.
Blinded nozzles, handholes and manways should be provided with new gaskets after completion of hydrostatic testing and painting.
1.5 Pneumatic Pressure Testing
Pneumatic pressure testing should not be accepted in lieu of hydrostatic testing on vessels.
All reinforcing, saddle and wear pads should be pneumatically tested with air and soapsuds at 15 psig (1 bar) prior to hydrostatic testing.
2.0 Protective Coatings
Supplier should provide external and internal coatings as specified.
Coating procedures, including pre-cleaning, surface preparation, application and products to be used should be reviewed and approved by Buyer prior to the start of the coating process.
The proposed procedures should be in accordance with the requirements listed in vessel data sheet and the (coating) product data sheets.
All coating work should be performed after completion of all fabrication and testing, including hydrostatic pressure testing and reinforcing pad air testing.
The entire vessel (including the inside of the skirt, outside of the bottom head, entire base ring, and all skirt attachments) should be coated.
- Nozzles should be painted on the flange edges, inside bolt holes, and up to the gasket surface.
- RTJ flange grooves should be protected during blasting and greased during painting operations.
Couplings should be tightly plugged with hex-head plugs during blasting and painting.
Bolt holes in vessel supports and attachments should be blasted and fully primed before assembly.
Ladders, cages, platforms and handrails should be hot-dip galvanized and/or coated.
3.0 Identification and Markings
Vessels should be provided with a stainless steel nameplate in accordance with the ASME Code.
The nameplate should include the following data as a minimum, which should be engraved or stamped into the nameplate:
- ASME Code Stamp (indicating degree of radiography and stress relief)
- National Board Registration Number
- Manufacturer's Name
- Manufacturer's Serial Number
- Year Built
- Maximum Allowable Working Pressure - Hot and Corroded (MAWP)
- Maximum Allowable Pressure - New and Cold (MAP)
- Corrosion Allowance
- Shell Material and Thickness
- Head Material, Thickness and Type
- Vessel Name (Service) and Tag Number
- Purchase Order Number
- Vessel Weights - Dry, Operating and Hydrostatic Test
- MDMT at MAWP
- Lowest allowable MDMT and coincident maximum pressure
Nameplates should be located so that they are easily accessible after installation.
On insulated vessels, the nameplate should be installed on a "T" or "U" bracket so as not to be covered or obstructed by insulation.
Nameplates should be securely attached to pressure vessels using one of the following methods:
- Seal-welding to shell or head prior to stress relief or hydrostatic testing
- Riveted (stainless steel) to a “T” or “U” bracket
- Bolted (stainless steel) to a “T” or “U” bracket with the nuts tack welded
The vessel name (service) and tag number should be painted or stenciled the on opposite sides of the vessel.
- Lettering should be black, 6" (150 mm) high capital block letters, and located on the shell horizontal centerline for horizontal vessels, and about 6'-0" (1.85 m) above the base plate for vertical vessels
- Horizontal vessels longer than 20'-0" (6 m) T/T, or greater than 8'-0" (2.5 m) in outside diameter should also include identification lettering on both heads
- Tall vertical vessels should include additional identification lettering at each operating level as specified by Buyer
Supplier should mark actual vessel dry weight on the shell and heads with paint sticks before shipping.
For vessels with internal coating or postweld heat treating, a warning should be painted on the outside of the vessel after completion stating: “This vessel is internally coated – depressure with care” and/or “This vessel has been postweld heat treated - no welding to this vessel is allowed.”
4.0 Preparation for Shipment and Storage
Supplier should be responsible for preparing vessels for shipment and storage in accordance with the required Commercial Terms and Conditions.
After fabrication, ladders, platforms, and other removable items supplied by vessel Supplier should be completely installed on the vessel in the shop to ensure proper fit-up, then disassembled and shipped separately.
- Each platform and ladder section should be identified with a metal tag, loosely wired to each section
- Loose shipped items should be properly tagged with the item name, the vessel name, and the tag number
All unpainted finished surfaces, e.g., flange gasket faces, threads, etc., should be coated with suitable rust preventive or grease.
- All bolting should be lubricated with thread lubricant prior to final installation
- Telltale holes in reinforcing and saddle pads should be plugged with heavy grease
All flanged openings should be protected with a flange cover, plastic sheet, and gasket.
- Flange covers should be constructed from exterior grade plywood, 1/2" (13 mm) minimum thickness, and secured with a minimum of 50%, or four (4) bolts, whichever is greater
- A plastic sheet should be inserted between the flange face and the wooden cover
- Threaded openings and couplings, except telltale holes in reinforcing pads and saddles, should be protected with a forged steel hex head pipe plug rated for the maximum allowable working pressure of the vessel
- Plugs should be either chromated/cadmium plated carbon steel or 316 stainless steel
Supplier should provide suitable supports for internal parts, which might be damaged during shipment.
- Temporary internal supports should be painted yellow, and the vessel should be clearly identified or tagged as having temporary internal supports
- If removal of the supports is required prior to putting the vessel into service, the Buyer should be notified in writing, with a drawing showing the supports to be removed
Supplier will submit for review and approval by Buyer, a written storage procedure for storage up to twelve (12) months.
All gauge glasses and cocks should be tagged, packed in clearly marked waterproof crates suitable for twelve (12) months outdoor storage, and shipped separately.
Supplier should be responsible for loading and securing vessels on transport truck/vessel at Supplier's manufacturing facility.
- The Supplier should provide the vessel with wood skids or crates to ensure protection against damage during shipment
- Supplier should provide Buyer at least one (1) week advance notice of vessel completion and delivery availability
If vessel is specified to be stored, Supplier should provide suitable type and quantity of desiccant for the stated storage period.
Desiccant should be placed in bags and tagged for ease of identification, removal and replacement.
Supplier should notify Buyer in writing of any special handling procedures, such as:
- Limitations on lifting or sling angles
- Restrictions on laying vertical vessels in the horizontal position
- Internal supports necessary for shipment
- Height restrictions, e.g., bridges, power lines, etc. along land transportation routes of the completed vessel(s)
Each removable piece of equipment that will be shipped separately from the vessel should be identified with a stainless steel tag.
- The tag should be securely wired to the equipment
- The identification tag should be die-stamped with the item number, platform number, piece number, and the total number of pieces
The identification tag should include the vessel tag name and number, to which each piece corresponds.
One full-sized copy of the approved vessel as-built drawings should be sealed in plastic and shipped with the vessel.
Supplier should clearly mark, in 2-inch (50 mm) letters, the proper information required to identify the items inside crates.
A “bill of lading” placed into a waterproof container should be attached to both the inside and outside of each crate.
If Supplier is responsible for shipping, Buyer should be notified at least one week in advance of the intended vessel delivery.
5.0 Documentation Requirements
Supplier should provide documentation in accordance with ASME Code and the vessel data sheet or Technical Requirements.
The following approval documentation should be submitted to Buyer for review and approval prior to the start of fabrication:
- ASME Code Calculations
- Buyer Required Calculations - Process and Sizing, Wind, Transportation, Lift, Center of Gravity, etc.
- Weld Map with WPS Identification (including MDMT identifications and welding sequences for critical joints, if requested by Buyer)
- Weld Procedure Specifications and Procedure Qualification Records
- General Arrangement and Elevation Drawing
- Fabrication Sections and Details
- General Design, Fabrication and Painting Procedures and/or Notes
Supplier approval submittals should include copies or prints per Buyer’s requirements.
Buyer reserves the right to relocate the vessel connections, clips, lugs, etc., before fabrication is begun.
Supplier should allow two (2) weeks for Buyer review and return of approval drawings.
Supplier's general arrangement and fabrication drawings should include the following information as a minimum:
- Plan, Elevation and End Views - fully dimensioned and drawn to scale
- Shell Thickness and Head Thickness and Type
- Details of all Vessel Internals and External Attachments
- Bill of Materials - component, material specs, quantities, ratings, and thickness
- Nozzle Schedule - mark, quantity, description, sizes, rating, type, thickness
- Flange ratings
- Nameplate Details - including dimensions and mounting details
- Vessel Weights - shipping, dry, hydrotest, operating normal and operating flooded (or 100% sand-filled, if applicable)
- Hydrostatic Test Pressure
- Radiography and NDE Requirements
- Weld details
- Surface preparation for coatings: external and internal
- Coating requirements: external and internal
- Clearance from main seams for attachments and penetrations
- Bill of materials
After completion of the vessel, Supplier should provide “Record Data Books” to Buyer. The Record Data Books should include the following documentation, as a minimum:
- ASME Code Data Report
- Drawings, Sections and Details (“As-Built”)
- Calculations (ASME Code and Buyer Required)
- Weld Procedure Specifications, Procedure Qualification Records and Weld/Welder Identification Maps
- Mill Test Certificates
- Fabrication and Inspection Records
- Hydrostatic Test Chart and Certificate
- Stress Relief Chart and Certificate (if applicable)
- Nameplate Rubbing or Photograph
- Operating and Maintenance Manual (if applicable)
Supplier should utilize industry standard drawing practices, as a minimum, in executing the work.
- For instance, all drawings should utilize title blocks and revision blocks for drawing identification and control
- All drawings should be dated and signed by appropriate Supplier representatives
- When revised, Supplier should identify revisions on drawings with clouds and revision triangles and the title and revision blocks should be appropriately completed with descriptions, dates, and signatures
Supplier should furnish final as-built drawings and data sheets in both hard copy and editable electronic formats.
For additional information on unfired pressure vessels, please see general pressure vessel requirements including engineering design and fabrication.