This document is no longer a CPR. This document implements the requirements of Corporate Procedure ESH100.2.PS.1, Control Pressure Safety Hazards.

IMPORTANT NOTICE: A printed copy of this document may not be the document currently in effect. The official version is the online version located on the Sandia Restricted Network (SRN).

4. PROCURING PRESSURE VESSELS AND SPECIAL SYSTEM COMPONENTS

Subject Matter Experts: Shane Page, and David Paoletta
Contributor: Pressure Safety Committee
MN471000, Issue R (Q not used)
Revision Date: October 8, 2007; Replaces Document Dated: August 29, 2007
Administrative Change: November 21, 2007, January 28, 2008, June 8, 2010, and May 26, 2011, and January 19, 2012

• OVERVIEW
• PROCURING PRESSURE VESSELS AND SPECIAL SYSTEM COMPONENTS
• STANDARD CHECKLIST
• PROCUREMENT
• Methods
• Material Toughness
• Design Considerations
• Fabrication
• Buying from Commercial Stock
• "Used" from Surplus or Previous Owner
• ASME CODE VESSELS
• ASME Code Stamp
• Advantages
• Disadvantages
• GENERAL PROCUREMENT PROCESS
• PRESSURE VESSELS FABRICATED TO THE ASME CODE BY CERTIFIED CODE SHOPS
• Checklist of Design Parameters
• Checklist of Contract Requirements
• CRYOGENIC SYSTEMS
• Procuring Cryogenic Systems
• LABELING PRESSURE SYSTEMS AND VESSELS
• Labeling
• Label Data
• RECORDS

OVERVIEW

This chapter describes the requirements for the design, fabrication, testing, and documentation of pressure vessels and special components. Special components are one-of-a-kind components for special applications that are not available as stock items from commercial suppliers. These components must meet the same requirements as vessels to assure an adequate margin of safety. The term "vessels" as used in this chapter shall include these special components.

PROCURING PRESSURE VESSELS AND SPECIAL SYSTEM COMPONENTS

Requirements

When procuring pressure vessels and special system components, Members of the Workforce shall ensure that they:

• Meet or exceed the requirements of this manual.
• Have:
• An adequate factor of safety.
• Proper materials and processes.
• An adequate overpressure test.

Guidance

Members of the Workforce should:

• Secure approvals at an early stage from representatives of the following functions:
  • Materials Application Engineering and Design Support contact.
  • Experimental Mechanics Department (1522) or the Mechanics of Materials Department (8776 ).
  • PA.
• Establish early liaison with an SNL buyer to expedite procurement of hardware or services.
• Use appropriate portions of the following checklist for procurement of pressure vessels, special system components, and services not available through the Just-in-Time (JIT) contract (see next topic).

STANDARD CHECKLIST

Requirements

1. Specify and define these operating conditions:
• Maximum Allowable Working Pressure (MAWP).
• Normal operating temperatures, and temperature extremes.
• Cyclic nature of pressure loading.
• Presence of hostile environments.
2. Select the design procedure.
• Select an appropriate design, preferably based on the use of Section VIII, Division 1, ASME Code, if applicable.
• Specify an adequate factor of safety as part of the design. (See Ch. 3, Selecting the Factor of Safety, for the process necessary prior to justifying a factor of safety of less than 3.5.)
3. Select or specify the materials and processes
• Consult the materials organizations as to the adequacy of the contractor's proposals, and specify the materials and processes to be used.
4. Specify an overpressure test and include these items:
• Test level, which is usually 1.3 X MAWP (see Ch. 6).
• Holding time at test pressure
• Temperature during test
• Instrumentation, measurements, and methodology desired
• Whether a Sandia representative is needed to witness the test
• Any special requirements.
5. Specify all documentation. This includes supplementary notes and any required certifications for fabrication and procurement that are specified in this chapter.

PROCUREMENT

Methods

Requirements

• Designed and built by SNL.
• Designed by SNL and built by outside contractor or by another DOE agency
• Designed and built for SNL by outside contractor or by another DOE agency
• Bought from a supplier's commercial stock
• Obtained "used" from surplus or previous owner.

Material Toughness

Requirements

• Ensure that custom pressure vessels in the first three categories above are constructed of required materials that meet, as a minimum, the toughness criteria from the ASME Code, Section VIII, Division 1, Paragraphs UG-20.

  Note:  The ASME Code addresses material toughness requirements for low-temperature properties of carbon and low-alloy steels for use in pressure vessels. Paragraph UG-20 of the Code may require impact testing on any of these materials if the design temperature/thickness of the material falls below the threshold values given in UCS-66. New welded-joint design requirements are addressed in UCS-68. Stress considerations are shown in Figure UCS-66.1.

• Ensure that pressure vessels bought from a supplier's commercial stock meet the ASME Code and are registered with the National Board
• Allow the use of the above materials for commercial pressure vessels with no further SNL requirement for impact testing per UG-84 if the pressure vessel is designed to the latest material toughness considerations addressed in the Div. I Code.

Design Considerations

Guidance

• If designed in-house, an ASME Code Stamp cannot be obtained for the vessel
• The preferred design approach is to use the ASME Code. Pressure vessel designers can select appropriate dimensions for a pressure vessel from the empirical equations, figures, and charts in Section VIII, Division 1, of the ASME Code. The ASME Code is recommended because of its simplicity and because it covers both vacuum and internally pressurized vessels. By following the rules of Section VIII, Division 1, of the ASME Code, the designer can fabricate an acceptable pressure vessel either in-house or by outside contract.
• Provide a complete set of design parameters.
• Obtain the Materials Application Engineering's approval of the materials.
• Obtain the following from the contractor before fabrication:
• Set of drawings
• Copy of the design calculations and certifications of the design criteria
• List of materials
• If an outside agency designs the vessel, indicate SNL's design approval by marking and documenting the set of drawings and returning them to the contractor.

  Caution: State in writing that SNL's approval of the drawings does not relieve the contractor of the obligation to supply a vessel conforming to specifications.

• Obtain an ASME Code vessel if the basic design parameters fall within the purview of the code.

Fabrication

• Specify that an outside contractor must furnish these certifications to document the pressure vessel work:
• Material properties (e.g., yield stress, ultimate stress, elongation, fracture toughness properties, etc.)
• Process specifications followed (e.g., weld, heat treat, stress relief)
• Inspection techniques and results (specify complete set of NDT evaluations required)
• Details of overpressure test and results (specify overpressure test procedures). Overpressure test may also be done in-house and is required before any vessel is used at SNL (see Ch. 6).
• Vessels designed and fabricated to the ASME Code by a Certified Code Shop are code-stamped and registered with the National Board of Boiler and Pressure Vessel Inspectors.

Buying from Commercial Stock

Requirements

• Determine the adequacy of pressure systems bought from a supplier's commercial stock for:
  • Pressure vessels in manned areas
  • Situations where potential equipment or facility damage or loss is unacceptable.

    Note:  The preferred procedure is to buy ASME and obtain an ASME Code stamp.

  Observe these principles when buying from a supplier's commercial stock, whether or not the vessel is ASME Code-stamped:

  • Manufacturer. Deal only with a reputable manufacturer, preferably one whose products are known to perform as advertised
  • Materials. Identify the material the vessel is made of, and obtain a material certification if possible
  • Calculations. Secure a set of the design calculations if possible
  • Factor of Safety. Quantify factor of safety consistent with definition given in Chapter 3
  • Overpressure Test. Determine whether an overpressure test was performed and, if so, what the test parameters were.

"Used" from Surplus or Previous Owner

Requirements

• Adequate factor of safety
• Proper material and fabrication process
• Adequate overpressure test

Members of the Workforce shall observe these principles when obtaining used vessels:

• If ASME Code-stamped, require documentation of history of use and validation of Code stamp. The Code stamp on components may be invalidated by:
  • Modifications made by a non-Code shop
  • Operations beyond the design limits of pressure or temperature
  • Corrosion beyond allowable amounts.
• If non-Code-stamped: Require documentation to show that the design standards were met originally and are still valid.

  Note:  The requirements for an adequate data package still must be met (see Ch. 9). Some used equipment that does not have sufficient, or any, documentation may require extensive testing to reestablish its adequacy. Lack of this effort or the costs associated with its accomplishment, may preclude the use of these items in a manned area. It may be less expensive, in some cases, to purchase a new item.

ASME CODE VESSELS

Introduction

Note:  This section discusses the advantages and disadvantages of procuring pressure vessels designed and built according to ASME Code from outside contractors, and outlines the general procurement process. This discussion applies only to vessels carrying "U" or "UM" stamps.

ASME Code Stamp

• Be aware that an ASME Code stamp is desirable and is recommended, but is not mandatory.
• Before selecting an ASME Code design procedure, determine if they want an ASME stamp. A "U" stamp is preferred over a "UM" stamp since the "U" stamp is applied when inspection is performed by a Code Inspector, not by an employee of the vessel manufacturer. The "UM" marking can be applied by an employee of the vessel manufacturer, when authorized by a Code Inspector.

  Note:  All pressure vessels for which an ASME Code stamp is obtained should be registered by the vendor with the National Board of Boiler and Pressure Vessel Inspectors. Unstamped vessels cannot be registered.

Advantages

Guidance

• Legal
• Code shop assumes limited responsibility for vessel failure
• Make use of industry-accepted standards.
• Economic
• Design and drafting costs are less
• Fabrication costs may be less
• Preparing a PSAR is simplified, if one is required.
• Design
  • Design is conservative
  • Assures that the design meets the PSM requirements.

Disadvantages

Guidance

• Economic
  • Fabrication costs may be more.
• Design
  • The design is conservative and may cause problems if size and weight are important
  • Does not normally cover size of less than 6 in. inside diameter, or an operating pressure of less than 15 psi, although in some instances a Code Stamp may be obtained
  • Provides for only these shapes:
    • Spherical
    • Cylindrical
    • Certain defined shells of revolution, or flat plates for the heads of cylindrical vessels.
  • Only the vessel is coded, not the bolted closures, piping, etc.
  • Modifications or repairs must be done by ASME Code shops.

  Materials

  • Limited to those listed in the ASME Code, Section VIII, Division 1
  • Information may not be state of the art
  • Not all the materials listed in Section VIII, Division 1, are acceptable to SNL in certain applications. The designer should therefore verify with the Materials Application Engineering (6219) that his preliminary selection from the list is satisfactory for intended use.

General Procurement Process

Members of the Workforce shall follow this process for procuring pressure vessels designed and built according to ASME Code from outside contractors.

PRESSURE VESSELS FABRICATED TO THE ASME CODE BY CERTIFIED CODE SHOPS

Note:  Certain requirements must be met to obtain a pressure vessel fabricated to ASME Code, Section VIII, Division 1, from an outside contractor.

Checklist of Design Parameters

Requirements

• Geometry.
• Maximum allowable working pressure.
• Operating temperature range.
• Working fluid
• Use cycle (e.g., 2 per hour, 6 per year).
• Material.
• Corrosion allowance.
• Overpressure-test requirement. Reminder: Test level=1.3 x MAWP.
• Special requirements (e.g., special closures, pressure relief devices, access doors, supports, inspections, environmental considerations for temperature and corrosion, additive finish).

Checklist of Contract Requirements

Requirements

• Design and fabricate in accordance with Section VIII, Division 1, of ASME Code

  Materials Note: SNL may request minimum charpy V-notch impact energies for parent material and weld material (fusion zone and heat-affected zone) at specific temperatures. (See ASME Code, Section VIII, Division 1, Table UG-84.)

• Vessel shall be Code-stamped and registered with the National Board
• Requester shall obtain fabrication drawings for approval before fabrication
• Requester shall obtain two copies each of the material certification, manufacturer's data sheets, and the inspection report before acceptance
• Address shipping and handling
• Vendor furnishes all hardware (e.g., bolts, nuts, gaskets, seals)
• Date(s) required.

CRYOGENIC SYSTEMS

Procuring Cryogenic Systems

Guidance

The purchasing organization is responsible for procuring cryogenic storage vessels and liquid cryogens.

LABELING PRESSURE SYSTEMS AND VESSELS

Labeling

Requirements

• Pressure vessels and other system components are labeled to identify them with the associated data package.
• Labels shall be affixed so that they do not detract from the vessel's strength or function.

Label Data

Requirements

• All Systems/Vessels
  • An identification name to reference it to the "Data Package".
• For ASME Code Vessels
  • Manufacturer's name and the year built
  • Manufacturer's serial number
  • MAWP and maximum operating temperature
  • Date and pressure level of overpressure test
  • Supplementary data as appropriate
• For Relief Valves
  • Serial number
  • Set pressure (verified by pressure test)
  • Date tested
  • Identification of the tester (PRV Test Station ID).

RECORDS

Requirements

Managers shall:

• Retain the Data Package as a permanent file for the life of the pressure system.
• Ensure that the required records are maintained, retrievable, and identified with the referenced hardware, including any reference to documented subsystems.
• Receive and retain Data Package information from the Space & Real Estate Management Department (4856) for systems that are acquired as part of a major facilities contract or under contract to a commercial contractor following inspection and acceptance by Department 4856.

  Note:  Data Package information will be turned over to the user organization at the time of occupancy or acceptance of the facility or system.

Guidance

Note:  For those components that do not have this information stamped on the items themselves, a copy of the appropriate page/section from the supplier's catalog with the item description and rating highlighted adequately documents this category of components.

Members of the Workforce should document system that contain components that have been custom designed and fabricated. These components are not listed in commercial suppliers' catalogs and the information to document the integrity of the vessel and component is generally more extensive. Optional information includes:

• Specifications and ratings.
• Design and as-built drawings.
• Calculations to support design factor of safety.
• Materials callout and any supplementary notes.
• Certification information, generally for Code vessels.
• Processing information such as welding, manufacturing techniques, or special materials treatments.
• Overpressure test accomplishment and results.

Note:  See Chapter 9 for documentation information.

Shane Page, srpage@sandia.gov
Al Bendure, aobendu@sandia.gov

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