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OSHA Interpretations:  Mechanical Integrity





              		      Most of the letters of interpretation issued by OSHA over the years have dealt with PSM applicability issues. This newsletter will focus on several interpretations dealing with the mechanical integrity (MI) element of the PSM Standard. In recent audits and other work, it is apparent that MI still represents an element of PSM that many companies have found difficult to successfully implement, particularly paragraph (j)(5), deficiency management. The reasons for this are many, however, the following are most prevalent:
  • MI covers a very broad set of activities and nearly every group, department, or discipline onsite has some responsibility for the program - MI is not just preventive the responsibility of the plant Maintenance Department.
  • Although it covers a wide range of activities and responsibilities, it is one of the elements in the Standard that is written in the most general, performance-based manner. MI requires a large amount of thought and interpretation to successfully implement.
  • Given the breadth of a MI program and the generality of the MI language, there has been only a moderate amount of written and verbal interpretation of the MI element by OSHA.

Interpretations of the Mechanical Integrity Element of PSM
The following interpretations of the MI element have been paraphrased and summarized for ease of reading and for space considerations in this article. The exact wording, including fuller explanations by OSHA made be found in the actual documents referenced.

  • If equipment types other than those listed in paragraph j(1) are important to safety, then MI applies to those types of equipment also (PSM Standard Preamble, OSHA letter of 5/24/94, OSHA letter of 7/11/94, OSHA letter of 11/30/94, OSHA letter of 12/7/95) 
  • Basic process control components (e.g., those that are embedded in the DCS and are not hard-wired or independent) should also be included in the MI program. This type of instrumentation and control equipment is covered by paragraph (j)(1)(v) of the PSM Standard, whereas emergency shutdown systems (or safety instrumented systems by recent definition in ANSI/ISA S84.01) are separately included by (j)(1)(iv) of the PSM Standard. Instrumentation and control equipment whose function has no safety function (i.e., relates to product quality or process performance only) do not need to be included in the MI program. (OSHA letter of 3/10/94)
  • ANSI/ISA S84.01-1996 has been recognized by OSHA as a "good engineering practice" for safety instrumented systems (SIS). OSHA does not specify or benchmark S84.01 as the only recognized and generally accepted good engineering practice for SISs. Based on input from stakeholders, OSHA stated in the PSM final rule that it did not intend to incorporate by reference into PSM all the codes and standards published by consensus groups. (OSHA letter of 3/23/00) Note: In September 1995, OSHA verbally clarified what they mean by a "good engineering practice." 

    A good engineering practice (GEP) is a consensus industry method of accomplishing some technical task. GEPs published by API, AIChE, ACC (formerly CMA), and others are sources of GEPs. Although employers cannot be cited for not following a particular GEP, OSHA will compare the practices it finds at PSM-covered sites and with published GEPs. OSHA also said that the basis for deviating from GEPs should be documented. (VPP Participant's Association Conference, September 1995)
     
  1. List of equipment in MI program should be compiled and prioritized. (Appendix C of PSM Standard - Non-Mandatory Guidance)
  2. Equipment on PM list should be prioritized so that more important equipment receives closer scrutiny (Appendix C of PSM Standard - Non-Mandatory Guidance.)
  3. Pressure Vessels & Storage Tanks: MI applies to tanks and vessels which are not pressurized as well as those that are pressurized (OSHA Instruction CPL2-2.45A CH-1 - PSM Compliance Directive, Appendix B)
  4. External inspections of MI-covered equipment should also include structural and weight-bearing equipment, as well as the effects of erosion. (Appendix C of PSM Standard - Non-Mandatory Guidance)
  5. Internal inspections of MI-covered equipment should include vessel shell, bottom and head; metallic linings; nonmetallic linings; thickness measurements for vessels and piping; inspection for erosion, corrosion, cracking and bulges; internal equipment like trays, baffles, sensors and screens for erosion, corrosion or cracking and other deficiencies. (Appendix C of PSM Standard - Non-Mandatory Guidance)
  6. MI applies if a vehicle (e.g., a rail car) is used as a temporary storage vessel (i.e., it is onsite and not "in transit"). (OSHA Letter of 7/11/94, OSHA co-sponsored PSM workshops in Spring 93)
  7. Maintenance may be specific to a group of equipment (not necessary for each individual piece of equipment) (OSHA Instruction CPL2-2.45A CH-1 - PSM Compliance Directive, Appendix B)
  8. Test and inspection documentation must record both positive and negative results, unless the procedure used to perform the task specifically states that the absence of a negative result means that the result was positive. In this case, the specific positive results do not have to be documented. (OSHA letter of 9/16/96)
  9. Equipment Deficiencies: Equipment found operating outside acceptable limits does not have to be shutdown if other protective measures and continuous monitoring are available, and the deficiencies are corrected in a "safe and timely manner." (OSHA Instruction CPL2-2.45A CH-1 - PSM Compliance Directive, Appendix B)
  10. MI quality assurance (design): "As built" drawings, together with certifications of coded vessels and other equipment, and materials of construction need to be verified and retained in the quality assurance documentation. (Appendix C of PSM Standard - Non-Mandatory Guidance)
  11. MI quality assurance (installation): Equipment installation jobs need to be properly inspected in the field for use of proper materials and procedures and to assure that qualified craftsmen are used to do the job. The use of appropriate gaskets, packing, bolts, valves, lubricants and welding rods need to be verified in the field. Also, procedures for installation of safety devices need to be verified, such as the torque on the bolts on ruptured disc installations, uniform torque on flange bolts, proper installation of pump seals, etc. (Appendix C of PSM Standard - Non-Mandatory Guidance)
  12. Records retention: Test and inspection records must be kept for the life of the process. (OSHA letter of 9/16/96, OSHA Region VI presentations on PSM in January 94)
  13. MI training must include portions of SOP's applicable to PM, safe work practices, MOC, and ERP (OSHA Instruction CPL2-2.45A CH-1 - PSM Compliance Directive, Appendix B)
Although verbal interpretations have no official standing and federal employees rarely speak for attribution, there have been a number forums following the adoption of the PSM Standard where OSHA representatives have made themselves available to speak about PSM and answer questions. These verbal Interpretations on MI contain some interesting information on OSHA's thinking (or at least the thinking of the person answering the question) The following verbal clarifications of the MI element of the PSM Standard have been made:
  • If a company can prove that control loops/other equipment can not be involved or contribute to a catastrophic release, and OSHA has no information to the contrary, certain loops/equipment may be exempted from MI program. (OSHA Region VI presentations on PSM in January 94)
  • Multiple failures: In determining whether certain loops/equipment are critical, OSHA will take into account multiple failures ("double jeopardy", maybe some "triple jeopardy" situations). (OSHA Region VI presentations on PSM in January 94)
  • Checks and inspections done to maintain the integrity of processes must be documented to help companies develop a comprehensive data base to enable them to change out parts before they fail. (AIChE PSM Symposium in Houston - February 94)
  • Employers cannot rely solely on vendor's QA/QC programs to meet MI requirements (MI cannot be inferred from vendor quality). (OSHA co-sponsored PSM workshops in Spring 93)
  • OSHA intends to apply same qualification criteria required for operator training program to maintenance technicians, including "grandfather" clause. Currently there is an inconsistency between process operator and maintenance technician training and qualification. This cannot be changed without a language change to the regulations themselves. (OSHA Region VI presentations on PSM in January 94)
  • To document maintenance technician skills training, the following are acceptable: a union training program, junior/community college training, in-house training, vendor training, Contractor training program (for contractors)  (OSHA Region VI presentations on PSM in January 94)
  • New construction: MI program should be in place before introducing hazardous chemicals. (OSHA Region VI presentations on PSM in January 94)

If you have an interpretation that you would like to share with AcuSafe or feedback about this feature, please email us at editor@acusafe.com.  To go back to the OSHA Interpretations Feature Index, click here or go back to AcuSafe.

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