VPP PSM SUPPLEMENT B
City, State
Evaluation Date
Report Date
VPP Evaluation Team
Name, Team Leader
Name, Backup Team Leader
Name, Safety Specialist
Name, Hygienist
Name, SGE
OMB Control Number: 1218-0239 Expires 04-30-2021
Public reporting burden for this collection of information is estimated to average 20 hours per response, including time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding the burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to the Directorate of Cooperative and State Program U.S. Department of Labor, 200 Constitution Ave., Suite N3700 NW, Washington, DC 20210-4537 and reference the OMB Control Number 1218-0239
Instructions for the 2013 Annual Site Evaluation Questions:
VPP participants whose operations are covered by the Process Safety Management (PSM) Standard must provide responses to each question that is applicable to their operations. Responses must cover all PSM-related operations. Please indicate that a question is “Not Applicable” if it addresses functionality outside the scope of the operations, and briefly explain why.
The questions for calendar year 2013 emphasize the elements of the employers’ pressure relief systems to include process equipment, piping, vessels and valves.
Resident Contractor VPP Participants covered by the PSM standard must also provide responses to each applicable question based on the guidance contained within each question. It is understood that a Resident Contractor does not likely operate process equipment per se, but contractor operations frequently impact on the Host’s PSM process-related operations. A sole reference of “Not Applicable” is not an adequate response. Resident Contractors are expected to be able to provide a narrative response to these questions based on how their operations relate to the Host’s PSM programs.
Supplement B PSM Questions - 2013 |
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VPP Annual Evaluation Questions |
List Type: General PSM |
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Similar design and design bases PSI are required for the rest of the relief system equipment downstream from the relief devices, i.e., relief vent lines, manifolds, headers, other relief disposal equipment, and flare stack.
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Guidance: API 520 Part 1-2008, Section 5.3.3.1.1 states, “Conventional PRVs show unsatisfactory performance when excessive backpressure develops during a relief incident, due to the flow through the valve and outlet piping. The built-up backpressure opposes the lifting force which is holding the valve open.” Section 5.3.3.1.2 states, “Excessive built-up backpressure can cause the valve to operate in an unstable manner. This instability may occur as flutter or chatter. Chatter refers to the abnormally rapid reciprocating motion of the PRV disc where the disc contacts the PRV seat during cycling. This type of operation may cause damage to the valve and interconnecting piping. Flutter is similar to chatter except that the disc does not come into contact with the seat during cycling.” In general, API 520 Part 1 Section 5.3.3.1.3 provides criteria stating, “In a conventional PRV application, built-up backpressure should not exceed 10 % of the set pressure at 10 % allowable overpressure…”, although certain conditions can exist to exceed 10% (See API 520 Part 1, Section 5.3.3). The flow-induced pressure drop in the inlet piping guidance is located in API 520 Part 2-August 2003, Section 4.2.2 “Size and Length of Inlet Piping to Pressure- Relief Valves When a pressure-relief valve is installed on a line directly connected to a vessel, the total non-recoverable pressure loss between the protected equipment and the pressure-relief valve should not exceed 3 percent of the set pressure of the valve except as permitted in 4.2.3 for pilot-operated pressure relief valves. When a pressure-relief valve is installed on a process line, the 3 percent limit should be applied to the sum of the loss in the normally non-flowing pressure-relief valve inlet pipe and the incremental pressure loss in the process line caused by the flow through the pressure-relief valve. The pressure loss should be calculated using the rated capacity of the pressure-relief valve. Pressure losses can be reduced by rounding the entrance to the inlet piping, by reducing the inlet line length, or by enlarging the inlet piping. The nominal size of the inlet piping must be the same as or larger than the nominal size of the pressure relief valve inlet connection as shown in Figures 1 through 3. Keeping the pressure loss below 3 percent becomes progressively more difficult at low pressures as the orifice size of a pressure-relief valve increases. An engineering analysis of the valve performance at higher inlet losses may permit increasing the allowable pressure loss above 3 percent. When a rupture disk device is used in combination with a pressure-relief valve, the pressure-drop calculation must include the additional pressure drop developed by the disk (see 4.6 for additional information on rupture disk devices).” Other references for this guidance include International Standards Organization (ISO) ISO 4126 Part 9 Section 6
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Guidance: API 576, Section 6 provides guidance into the inspection of relief devices. Section 6.1.1 states, “Failure of pressure-relieving devices to function properly when needed could result in the overpressure of the vessels, exchangers, boilers, or other equipment they were installed to protect. A properly designed, applied, and installed pressure-relieving device that is maintained in good operating condition is essential to the safety of personnel and the protection of equipment during abnormal circumstances. The principal reason for inspecting pressure-relieving devices is to ensure that they will provide this protection.
API 576, Section 5 discusses examples of “Causes of Improper Performance”. More detail is provided in this section, but a brief overview in Section 5.2.2 states, “There are many causes of damaged valve seats in refinery or chemical plant service, including the following. a) Corrosion. b) Foreign particles introduced into the valve inlet and pass through the valve when it opens, such as mill scale, welding spatter or slag, corrosive deposits, coke, or dirt. The particles may damage the seat contact required for tightness in most pressure-relief valves. The damage can occur either in the shop during maintenance of the valve or while the valve is in service. c) Improper or lengthy piping to the valve inlet or obstructions in the line. These can cause a valve to chatter. The pressure under the seat may become great enough to open the valve. However, as soon as the flow is established, the built-up pressure drop in the connecting piping may be so great that the pressure under the seat falls and allows the valve to close. A cycle of opening and closing may develop, become rapid, and subject the valve seating surfaces to severe hammering, which damages the seating surfaces, sometimes beyond repair. Figure 27 and Figure 28 show seating surfaces damaged by chattering and frequent fluctuations of pressure. d) Careless handling during maintenance, such as bumping, dropping, jarring, or scratching of the valve parts. e) Leakage past the seating surfaces of a valve after it has been installed. This leakage contributes to seat damage by causing erosion (wire drawing) or corrosion of the seating surface and thus aggravating itself. It may be due to improper maintenance or installation such as misalignment of the parts, piping strains resulting from improper support, or complete lack of support of discharge piping. Other common causes of this leakage are improper alignment of the spindle, improper fitting of the springs to the spring washers, and improper bearing between the spring washers and their respective bearing contacts or between the spindle and disk or disk holder. Spindles should be checked visually for straightness. Springs and spring washers should be kept together as a spring assembly during the life of the spring. Seat leakage may also result from the operating pressure being too close to the set pressure of the valve. f) Improper blowdown ring settings. These can cause chattering in pressure-relief valves. The relief valve manufacturer should be contacted for specific blowdown ring settings for liquid service and for vapor service. g) Severe oversizing of the pressure-relief valve for the relief loads encountered can cause the valve to close abruptly, resulting in disc and nozzle seating surface damage.”
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1. The original thickness measurements for all piping 2. The locations of subsequent thickness measurements 3. The dates subsequent thickness measurements were taken 4. The results of the subsequent thickness measurements
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Supplement B PSM Questions - 2013 |
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VPP Annual Evaluation Questions |
List Type: General PSM |
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Supplement B PSM Questions - 2013 |
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VPP Annual Evaluation Questions |
List Type: General PSM |
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VPP PSM Supplement B - 2013 |
File Type | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
File Title | VPP PSM SUPPLEMENT A |
Author | elahaie |
File Modified | 0000-00-00 |
File Created | 2021-04-24 |