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6151
Pressure Systems |
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1.0 Introduction
The hazards associated with pressure systems include rupture and explosion. Hazards associated with systems under vacuum include, but are not limited to, failure due to backfill pressurization, rupture, and implosion. Significant considerations in addition to pressurization include catastrophic failure of thin windows.
Causes of pressure systems failures include:
· inadequate design, fabrication and testing
· failure to consider all probable failure scenarios
· failure to properly maintain a pressure system for its rated service
· exceeding the rated operating conditions of the pressure system
· failure to provide adequate over-pressure protection devices
· improper modifications
Examples of pressure systems used at Jefferson Lab include:
· Cryomodules, which include both pressure and vacuum systems
· Experimental equipment with vacuum chambers above 15 psi
· Small experiment-target vessels and piping confining pressures above 15 psi
· Superconducting magnets, which include both pressure and vacuum systems
· Oil-removal and gas-storage systems integral to the cryogenic plants
· Compressed-air and pressurized air reservoirs above 15 psi
· Heating and cooling water systems throughout the site
The pressure systems program at Jefferson Lab ensures pressure systems safety by establishing:
· Requirements for the design, fabrication, testing, inspection, maintenance, repair and operation of pressure systems.
· A Pressure Systems Committee (PSC).
· Formalized documentation for each pressure system.
· A quality control system for the fabrication of pressure system components.
· Training and qualification procedures for operators of pressure systems.
Pressure vessel requirements
For design, fabrication, testing, repair and inspection are based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section VIII, Rules for Construction of Pressure Vessels.
Piping system requirements
For design, fabrication, testing and inspection are based on the ASME Code for Pressure Piping B31. ASME Code B31.3, Process Piping, shall be the primary code of reference for Jefferson Lab piping systems. The Design Authority shall incorporate other applicable codes where necessary based on sound engineering judgment and proven working experience and practice.
ES&H Manual Chapter 6150 Compressed Gases and ES&H Manual Chapter 6500 Cryogenic and ODH Safety are to be referenced for additional requirements for specific uses.
Users/experimenters planning to incorporate pressure or vacuum systems in a physics experiment must also comply with ES&H Manual Chapter 3120 The CEBAF Experiment Review Process and its appendices or FEL users must comply with ES&H Manual Chapter 3130 The FEL Experiment Review Process and its appendices. Although all the provisions of the present chapter apply, users/experimenters must address them within the larger context of the experiment review process.
2.0 Hazard Avoidance
Key hazard avoidance aspects of pressure systems include the following:
· Design, fabricate and test pressure systems according to the requirements set forth in this chapter.
· Never exceed the rated capacity of a pressure system except during system test qualification.
· Use the pressure system only for the purpose it was designed to serve.
· Do not modify pressure systems or their associated piping and fittings without documented authorization using the provisions of this chapter.
· Never apply heat to a pressure system except as may be specifically authorized by work procedures which reflect the pressure system design criteria. An example of an exception is the bake out of vacuum systems and some cryogenic systems.
· Provide for routine inspections of pressure vessels.
· Report knowledge of damage or apparent defects to the appropriate supervisor.
3.0 Key Terms
American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code. The national consensus code used as the standard for pressure vessel design, fabrication, testing and inspection at Jefferson Lab. The most frequently used sections of the ASME BPV Code as applied to pressure vessels at Jefferson Lab are:
· Section II: Materials, Parts A, B, C, and D
· Section V: Nondestructive Examination
· Section VIII: Rules for Construction of Pressure Vessels, Divisions I & II
· Section IX: Welding and Brazing Qualifications
ASME Code for Pressure Piping B31. The national consensus code used as the standard for piping system design, fabrication, testing and inspection at Jefferson Lab. Sections of B31 which apply to piping systems at Jefferson Lab include:
· B31.1 Power Piping
· B31.3 Process Piping*
· B31.5 Refrigeration Piping
· B31.9 Building Services Piping
*ASME B31.3 Process Piping shall be used as the primary standard for Jefferson Lab piping systems. Other sections shall be applied as appropriate based on sound judgment of the Design Authority and proven practices in the respective field.
Pressure Systems Committee (PSC). A committee chartered to serve as both a steering committee for pressure safety implementation and the final Jefferson Lab authority for the approval of qualifications of materials and components that have not been considered by the ASME codes. The members of the PSC shall include the Engineering Manager (or designee as necessary) who shall also serve as the initial chair of the PSC; a Cryogenic System Engineer (CSE); a Mechanical Engineer for Superconducting Radio Frequency Structures (MESRFS); a Facilities Management Engineer (FME), an Experimental Hall Engineer (EHE); an Environmental, Safety, Health & Quality (ESH&Q) representative; and other technical experts appointed by the chairperson. The chairpersonship can be a co-chair arrangement and shall be rotated on a yearly basis. Committee membership is for a minimum of 18 months. The ESH&Q representative shall maintain the current membership list for the committee and provide for site-wide accessibility to that list.
4.0 Responsibilities
ESH&Q Division:
· Shall manage the site-wide Jefferson Lab Welding and Brazing Program included in ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program.
· Shall support, oversee and/or supervise, as needed, the code inspector.
· Shall provide inspection as required by ASME codes or by engineering requirements.
· Monitor current requirements and certifications necessary for examination and inspection personnel.
· Shall provide access to ES&H Manual, procedures and forms.
· Shall provide periodic assessment of processes and documentation.
Division Head
· Shall designate Design Authorities qualified per the requirements of this chapter.
· Shall verify that all groups within their division have a program in accordance with ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program.
· Shall verify that all recordkeeping requirements for pressure systems are in compliance with this chapter.
· Shall ensure that pressure system design, fabrication and testing meets ASME code requirements according to the policy set forth in this chapter.
· Where established codes cannot be directly applied because of pressure range, vessel geometry, use of special material, etc., measures to provide equivalent protection and ensure a level of safety greater than or equal to the level of protection afforded by the ASME codes shall be applied.
· Shall follow standards and procedures for mechanical design, fabrication and testing of pressure systems using the Pressure System Design, Pressure System Pressure Testing, and Pressure System Project Implementation and Documentation Guidance Appendices as outlined in this chapter.
· Shall follow standards and procedures for design, fabrication and examination of welds and brazes for pressure systems specified in ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program.
· Shall initiate and maintain pressure system documentation in a project file consistent with the requirements specified in ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance.
PSC Chair
· Shall brief the Directors Safety Council (DSC) periodically on committee activities.
· Shall ensure that the PSC meets periodically to:
o Develop and maintain program specifications covering design, fabrication, pressure testing, inspection, and documentation to incorporate the requirements of this policy.
o Maintain a referral list of pressure systems Design Authorities.
o Ensure the conduct of Peer Reviews for pressure system designs where qualifications of materials and components that have not been considered by the ASME codes are being requested.
o Be the final Jefferson Lab authority for the approval of qualifications of materials and components that have not been considered by the ASME codes.
o Document decisions and variances considered by the committee and forward copies to Design Authority for inclusion in the project file.
Facilities Manager
· Shall maintain required inspection and report documentation for all pressure vessels.
Chief
Information Officer
· Shall maintain a centralized database for the collection of all pressure systems records to include, at a minimum, design documentation, fabrication documentation and pressure test standards and procedures.
· Shall assist Design Authority and quality assurance, fabrication, purchasing, and facilities personnel with implementation of documentation control for pressure systems.
Everyone at
· Shall refer pressure system matters to the responsible Design Authority or the PSC.
· Before adding, moving, or modifying pressure systems associated with the normal physical plant – such as HVAC equipment, boilers, etc., shall consult the Maintenance Services Manager.
· Shall inform the appropriate Design Authority, PSC, or Division Head if you know or suspect that:
o a pressure system planned for use on site does not conform to the intent of the ASME codes, or
o a vessel, piping system or associated equipment such as a pressure relief device, is unsafe.
5.0 Qualifications
Design Authorities must demonstrate ability to design and construct pressure systems according to the applicable ASME codes. The qualifications and experience required of the Design Authority shall depend on the complexity and criticality of the pressure system and the nature of the individual’s experience. Jefferson Lab’s Engineering Manager approval is required if the individual does not meet at least one of the following criteria:
· Completion of an engineering or physics degree, requiring four or more years of full-time study, plus a minimum of five years experience in the design of related pressure vessels or piping.
· Professional Engineering registration, recognized by the local jurisdiction, and experience in the design of related pressure vessels or piping.
Welders and Brazers must maintain qualifications for the types of fabrication associated with pressure system construction. For Class A and B welds and brazes (see ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program for definitions) qualifications for pressure systems are given in Articles III and XIII of the ASME BPV Code, Section IX. Similar rules given in American Welding Society (AWS) construction codes may also apply provided they are the same or stricter than the ASME requirements or where the ASME requirements are not applicable. For piping systems, ASME B31 Codes provide modified requirements that take precedence over ASME BPV Code Section IX.
Inspectors must meet the following qualifications:
· For pressure systems to be used at Jefferson Lab, the Inspector shall be designated by Jefferson Lab and shall be an employee of Jefferson Lab, an employee of an engineering or scientific organization, or of a recognized insurance or inspection company acting as Jefferson Lab’s agent. The Inspector shall not represent nor be an employee of the pressure system manufacturer, fabricator or erector unless Jefferson Lab is also the manufacturer, fabricator, or erector.
· For pressure vessels built by Jefferson Lab but used elsewhere, this person must be an Authorized Inspector who must be regularly employed by an ASME accredited Authorized Inspection Agency, i.e., the inspection organization of the Commonwealth of Virginia, or an insurance company authorized to write boiler and pressure vessel insurance.
· The Inspector shall have not less than 10 years experience in the design, fabrication, or inspection of industrial pressure systems. Each 20% of satisfactorily completed work toward an engineering degree recognized by the Accreditation Board for Engineering and Technology shall be considered equivalent to one year of experience, up to five years total.
· In delegating performance of inspection, the Inspector is responsible for determining that a person to whom an inspection function is delegated is qualified to perform that function.
Examiners must have training and experience commensurate with the needs of the specific examinations. ASNT Recommended Practice No. SNT-TC-1A is a required ASME BPV guideline for qualifying and certifying NDE personnel.
Operators of pressure, vacuum, and process piping systems must have hazard awareness training that includes basic principles of pressure technology and pressure safety. Operators shall also be given on-the-job training that is system specific, focusing on the expected performance of the system, direction for noticed deviations from expected performance, and clearly defined operating procedures for the system.
6.0 Program and Procedure Summary
Jefferson Lab has safety policies and procedures that ensure all pressure systems are designed, fabricated, tested, inspected, maintained, repaired, and operated by trained and qualified personnel in accordance with applicable and sound engineering principles.
Jefferson Lab further verifies that all new pressure systems designed and fabricated following the effectivity date of the original revision of this chapter (2/28/08) shall conform to the applicable:
· ASME BPV Code, Sections I through XII including applicable code cases;
· ASME Code for Pressure Piping B31;
· and to the strictest applicable state and local codes.
For new pressure systems where these ASME codes cannot be directly applied because of pressure range, vessel geometry, use of special material, etc., Jefferson Lab shall implement measures to provide equivalent protection and ensure a level of safety greater than or equal to the level of protection afforded by the ASME codes. Measures shall include:
· Design drawings, sketches, and calculations must be reviewed and approved by a qualified independent design professional or a documented Peer Review.
· Qualified personnel shall be used to perform examinations and inspections of materials, in-process fabrications, non-destructive tests, and acceptance test.
· Documentation, traceability, and accountability shall be maintained for each unique pressure vessel or system, including descriptions of design, pressure conditions, testing, inspection, operation, repair, and maintenance.
Jefferson Lab’s policy is to apply ASME codes where practical to vacuum system design. If a vacuum system can be pressurized to above 15 psi under regular or failure conditions, the ASME code must be applied to its design, fabrication and testing.
For pressure vessels where the ASME BPV Code can be directly applied, reasonable diligence shall be extended to procure the vessel from a company authorized to use the ASME “U” or “UM” Stamp to construct ASME Section VIII Pressure Vessels. Where the limitations of otherwise qualified vendors precludes “U” or “UM” stamping, the vendor (or Jefferson Lab if the vessel is to be fabricated in-house) shall comply with all applicable sections of the ASME BPV Code except for those involving stamping.
The pressure systems of the normal physical plant, including unfired and fired pressure vessels such as HVAC equipment and boilers, are maintained under the supervision of the Mechanical/Electrical Maintenance Section Manager. No addition, movement, or modification of any such vessel or piping system is to be made without consulting with the manager.
ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance provides requirements and guidance for design, fabrication and installation of a pressure system at Jefferson Lab. Figure 1, Pressure Systems Project Flow Chart provides a pictorial representation of the suggested pressure system process flow and points the reader to the applicable Technical Appendix for each step of the process.
Figure
1. Pressure
Systems Project Flow Chart
6.1
Designing a Pressure System
Pressure systems must be designed using sound engineering practices to satisfy the needs of Jefferson Lab. The design must be evaluated using the guidance provided in the ASME BPV and B31 Piping Codes. ES&H Manual Chapter 6151 Appendix T2 Pressure System Design Program provides requirements and guidance in designing pressure systems. Design Authorities planning or designing pressure systems must perform the following steps:
1. Determine whether the proposed design fits the definition of pressure system provided in this chapter.
2. Initiate a project documentation folder and a project checklist according to the requirements provided in ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance, if the proposed design meets the definition of a pressure system.
3. Define design criteria and applicable ASME codes.
4. Complete design calculations, drawings and specifications per the applicable codes. The Design Authority shall determine weld/braze classifications (see ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program) and include those classifications on design drawings or sketches. If ASME codes cannot be directly applied because of pressure range, vessel geometry, use of special material, etc., the Design Authority must ensure a level of safety greater than or equal to the level of protection afforded by the ASME codes. Components of pressure systems such as thin windows call for additional controls to verify safety. Special guidance for thin window design is given in ES&H Manual Chapter 6151 Appendix T3 Safety Requirements for Thin Window Design.
5. Conduct required Peer Reviews and, if appropriate, design reviews.
6. Include pressure system design documentation such as calculations, drawings, specifications, references, parts lists, etc. in the project folder. Required design documentation is presented in ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance.
6.2
Acquiring an
Off-Site Manufactured Pressure System
The Design Authority shall verify that off-site manufactured pressure systems and pressure components comply with the design documentation and meet applicable quality assurance requirements by following these steps:
1. Determine the quality assurance requirements and the applicable ASME code requirements prior to acquiring a manufactured pressure system or pressure system component. Consult the Quality Assurance Representative for assistance.
2. Develop Statement of Work which includes applicable drawings, references technical specifications and identifies required documentation and inspection reports.
3. Follow the Jefferson Lab purchasing process.
4. Work with the manufacturer to ensure ASME codes or their equivalent (verified by Peer Review) are implemented throughout the design, fabrication and any initial pressure testing of the pressure system.
5. Verify ASME applicable pressure vessels are identified with the ASME certification “U” or “UM” stamp. Fabrication, testing, and certification shall be performed by a manufacturer or assembler holding the appropriate certificate. A copy of the Manufacturer Data Report, signed by the manufacturer’s representative and the National Board commissioned inspector shall be received and forwarded to the Facilities Management Department.
6. Verify that pressure relief devices have the proper marking as required by the ASME BPV Code.
7. Verify receiving inspections are performed. Examples of receipt inspection include but are not limited to inspection for shipping damage, correct visible nameplate data, evidence of compliance with design documentation, and received documentation. Contact Purchasing and the Quality Assurance Representative for assistance.
8. Include documentation for off-site manufactured pressure systems in the project folder. Examples of required documentation are provided in ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance.
6.3
Fabricating
a Pressure
System
Design Authorities shall verify that pressure systems fabricated at Jefferson Lab comply with the design documentation and meet applicable quality assurance requirements. Documented Peer Review approval is required where ASME code fabrication requirements cannot be directly applied.
Receipt inspection of materials and components used in the fabrication of a pressure system must be performed. Examples of receipt inspection include, but are not limited to, inspection for shipping damage, material certifications, correct visible nameplate data when required, evidence of compliance with design documentation, and received documentation. Contact Purchasing and the Quality Assurance Representative for assistance.
Materials and components designated for pressure system fabrication must be clearly marked as such with appropriate documentation attached as applicable.
All welded and brazed pressure systems must be fabricated and examined in accordance with ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program.
For pressure systems fabricated at Jefferson Lab but used elsewhere, the Design Authority shall verify that inspections by Authorized Code Inspectors are performed as required.
6.4
Installing
and Pressure
Testing a Pressure
System
Pressure systems must be installed and inspected to comply with design documentation, quality assurance and code requirements. Except for unmodified pressure vessels properly stamped as required by the ASME code, all new and modified pressure systems at Jefferson Lab must be tested in accordance with ES&H Manual Chapter 6151 Appendix T4 Pressure Systems Pressure Testing Program. For minor repairs or additions, the Design Authority may waive pressure testing provided precautionary measures have been implemented to assure sound construction.
The Design Authority and Quality Assurance personnel must follow these steps for all pressure systems installations requiring pressure testing:
1. Installation shall be performed by qualified personnel with training and experience in the specific type of installation.
2. After installation is complete and before normal operation is initiated, a pressure test must be conducted and documented. Pressure testing includes hydrostatic and/or pneumatic testing per ES&H Manual Chapter 6151 Appendix T4 Pressure Systems Pressure Testing Program.
3. Forward all pressure testing and installation documentation to Design Authority for inclusion in the project folder.
4. Designated Quality Assurance personnel shall participate in a final safety walk through before operation. All requirements of the QA Project Checklist including design documentation, required material and component identification, shall be met. Documented results of this final inspection shall be provided to the Design Authority for retention in the project folder.
6.5
Operating
and Maintaining a Pressure
System
All pressure systems shall be maintained and operated in accordance with the approved design criteria:
· Operators must be trained in the operational characteristics of the system, understand the operational procedures, checklists, and inherent hazards associated with the system and be knowledgeable in lockout/tagout and emergency procedures.
· Documentation of operator training shall be maintained in the Jefferson Lab training database.
· Operators must regularly check the pressure system considering the following items:
o Check pressure relief valves, gages, rupture disks, system components and piping for leaks, degradation, corrosion and blockage.
o Verify valve positions are correct prior to operation and after any system changes.
o Monitor and maintain systems within operational parameters with installed instrumentation.
6.6
Inspecting a
Pressure
System after Initial Operation
Pressure vessels shall be inspected at intervals set by the Virginia Safety and Health Code Board according to requirements of the Code of Virginia Title 40.1 Chapter 3.1 and the Virginia Safety and Health Code Board Boiler and Pressure Vessel Rules and Regulations 16VAC 25-50-10. To the extent practicable, pressure vessels must be installed so that any inspection openings are accessible. The Facilities Manager is responsible for conducting these inspections and maintaining inspection records.
6.7
Taking a Pressure System
Out of Service
If a pressure system is required to be taken out of service, adequate measures must be provided to protect worker safety, environmental safety and equipment. Contact the Facilities Manager for methods to control potential hazards from corrosive, toxic, flammable or explosive contents.
6.8
Repairing or
Modifying a Pressure
System
Repairs or modifications to pressure systems must be completed under the direction of a Design Authority. See ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance for specific information.
Repairs to piping systems shall be made using sound engineering principles. Modifications to piping systems shall be made using current ASME codes and/or documented equivalent measures. Documentation for both repairs and modifications shall follow the requirements provided in ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance.
Repairs/modifications to stamped pressure vessels shall be performed by an organization that is authorized to use the National Board R stamp. Repairs/modifications to stamped pressure vessels shall be coordinated by the Facilities Manager. Repairs/modifications to non-stamped pressure vessels that were constructed according to the ASME code but were not stamped shall be pressure tested prior to being placed in service. Repairs/modifications to pressure vessels where ASME codes cannot be directly applied shall be performed using measures equivalent to the protection afforded by the ASME codes. Documentation shall follow the requirements provided in ES&H Manual Chapter 6151 Appendix T1 Pressure System Project Implementation and Documentation Guidance.
Changing the service of a pressure vessel or piping system is also viewed as a modification. Changing the service can mean any change in the application or change in the location of the vessel or piping if the structural support is affected.
7.0 List of Appendices
· ES&H Manual Chapter 6151 Appendix T2 Pressure Systems Design Program
· ES&H Manual Chapter 6151 Appendix T3 Safety Requirements for Thin Window Design
· ES&H Manual Chapter 6151 Appendix T4 Pressure Systems Pressure Testing Program
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ISSUING
AUTHORITY |
CHAPTER
AUTHOR |
APPROVAL
DATE |
EFFECTIVE
DATE |
EXPIRATION
DATE |
REV. |
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ESH&Q Division |
06/24/08 |
06/24/08 |
06/24/11 |
2 |
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