FM Global offers FREE GUIDANCE on implementing a “car seal” program

As I have said before, I am a huge fan of Global FM’s Data Sheets, as these FREE data sheets provide EXCELLENT information for businesses who may not have the funds or the ability to use other codes.  And today I got a notice that FM revised their data sheet 7-49, Emergency Venting of Vessels and this revision centers around doing maintenance when we have Installations with Intervening Stop Valves on Pressure Relief Devices (2.1.2 Design of the Emergency Overpressure Relief System).  In this revision, FM does a very nice job defining what our management system should look like when we have installations with intervening stop valves on pressure relief devices…

emphasis added by me

2.1.2.1.10 Do NOT install manual stop valves (shutoff valves, isolation valves) on either the inlet or discharge side of pressure relief devices (see Section 3.1.5).

2.1.2.1.10.1 If it is necessary to work on a pressure relief device while the protected equipment/system is operating, install redundant pressure relief devices and provide valve operation controls to ensure that manual stop valves in the pressure relief path are in their proper position (open or closed). This could include:

A. A three-way switching valve (so that one device ALWAYS remains in service). See Fig. 3.

B. Mechanical or instrumented interlocks designed to prevent valve operations that could result in blocking the pressure relief path before an alternate path is put into service. 

2.1.2.1.11 Installations with Intervening Stop Valves on Pressure Relief Devices

2.1.2.1.11.1 General

Where intervening manual stop valves are currently installed or proposed at the inlet or discharge side of pressure relief devices protecting a vessel and/or piping system, adhere to ALL of following recommendations (A through J):

1. Ensure P&IDs show ALL intervening stop valves in the pressure relief system.
2. Ensure stop valves are in the FULL OPEN position whenever the pressure relief valve is in service.
3. Pre-plan and document procedures to isolate a pressure relief device from the vessel and/or piping system to minimize the time required to inspect, test, repair, or replace the relief device.
4. Authorize ONLY specifically trained personnel (including operators and maintenance staff) to open or close a manual stop valve to isolate a pressure relief device from operating equipment or piping systems using documented procedures. 
5. Use a documented lock-out/tag-out system whenever any intervening manual stop valve is CLOSED for inspection, testing, repair, or replacement to ensure they are reopened promptly after completion of the activity.
6. Verify the position of ALL intervening manual stop valves prior to any unit startup.
7. Design each intervening manual stop valve to have a FULL BORE PORT larger than or equal in size to the inlet and/or discharge (as applicable) of the pressure relief device.
8. Design, configure, and/or orient the intervening manual stop valve to prevent an internal failure of the stop valve from closing and/or blocking the pressure relief path. For example, install gate valves with the valve stem oriented at or below the horizontal position.
9. Design and install any intervening manual stop valves for the service conditions and so that the valve position can be visually verified.
10. Secure ALL intervening manual stop valves in the open position using locks (with or without chains) or car seals. Ensure the locks or car seals are suitable for the service conditions and installed so they must be opened or broken to operate the manual stop valve.
11. Perform MONTHLY inspections to verify the intervening manual stop valve is OPEN and the lock or car seal has NOT been removed or broken. Maintain and review the records of the inspections as part of the site maintenance program.

2.1.2.1.11.2 Equipment/Piping Systems with Multiple Pressure Relief Devices

1. Adhere to all the recommendations in Section 2.1.2.1.11.1.
2. Provide each pressure relief device with a separate connection to the vessel and/or piping system, or a single connection supplying multiple devices such that isolating one relief device will not reduce the venting capacity below that required by the vessel operation (e.g., three relief devices where any two can provide adequate relief capacity).
3. Provide interlocks or administrative controls (documented operating procedures) to prevent more than one relief device being isolated during vessel operation.

2.1.2.1.11.3 Equipment/Piping Systems with Single Pressure Relief Devices

Where an intervening manual stop valve is installed on the inlet and/or discharge side of the only relief device protecting a vessel or piping system, do the following:

1. Adhere to all the recommendations in Section 2.1.2.1.11.1.
2. During isolation of the pressure relief device for maintenance or repair during vessel operation, ensure the following:
   1. An authorized person continuously monitors the pressure in the vessel.
   2. The authorized person is dedicated to this task and has no other duties when performing the task.
   3. The authorized person is capable of responding promptly in the event of overpressure conditions with documented, pre-defined actions covering all sources of possible overpressure that either stop the source of the overpressure (e.g., stop filling the vessel) or open alternate means of pressure relief (e.g., a vessel dump valve).
   4. The documented actions are capable of stopping the continuing overpressure condition. In the case of runaway reactions, there must be time to accomplish this task; some runaway reactions occur so fast that this cannot be achieved.
   5. The documentation is specific to the impaired relief device, not generic to devices on many different vessels with various operating conditions.

…

3.1.5 Manual Intervening Stop Valves Around Pressure Relief Devices

The use of manual stop valves (shutoff valves, isolation valves) on either side of pressure relief devices is NOT considered generally accepted the good practice. However, intervening manual stop valves are sometimes installed for process functionality at the inlet and/or discharge of pressure relief devices for inspection, testing, repair, or replacement purposes. When this is done, additional precautions are needed to minimize the likelihood of unintended closure during equipment operation (see Section 2.1.2.1.10). The best option on the inlet side of pressure relief devices is a three-way switching valve (Fig. 3). A three-way switching valve has an adequate inlet internal cross-sectional area for pressure relief and is designed to prevent a flow path from being blocked without another path being simultaneously open. There is NO intermediate position that allows both pressure relief devices to be isolated from the protected vessel and/or piping system at the same time. 

Another example of the use of intervening stop valves is multiple pressure relief devices installed with a connection to the vessel and/or piping system (e.g., three relief devices where any two can provide adequate relief capacity) with mechanical or instrumented interlocks to prevent all devices from being isolated simultaneously.
The ASME Boiler & Pressure Vessel Code, Section VIII Division I, UG-135 and Appendix M, Section M-5 (2015) or National Board Inspection Code NB 23, Part 1 (2015) provide criteria for the use of intervening manual stop valves. This document provides guidance that is consistent with these code requirements (see
2.1.2.1.11).

I encourage you to sign up for FREE access to FM’s Data Sheets.  I am not sure how OSHA would view them from a compliance position, but they are EXCELLENT resources for managing our risks.  The steps listed above in A-K are those steps needed to comply with ASME Section VIII, Appendix M which is a CODE REQUIREMENT – so the FM Data sheet is NOT a requirement, it is a TOOL to help us comply with code(s) and manage our risks properly.

Please read my other postings regarding Car Seal programs and Butterfly valves used in relief systems.

Disclaimer:  Although I have been writing about FM Global’s Data Sheets for many years, the company recently joined the ranks of my Corporate Partners in 2014.  

This post is NOT a paid endorsement for Global FM nor did FM ask me to post this.  I got the revision alert as all subscribers to their data sheets got.  Global FM no longer pays an annual membership fee BECAUSE they offer their data sheets for FREE.