1.01.003 Pressure Relief Valves (PRV)

Purpose

The purpose of this procedure is to establish the minimum requirements for performing inspection and replacement of the Pressure Relief Valve (PRV) on Flogistix compressor packages. Also, to ensure the Pressure Relief Valve is the correct set pressure for the vessel or piping where it is installed in accordance with this procedure.

The Pressure Relief Valve (PRV) is a type of valve used to control or limit the pressure in a system which can build up for a process upset, instrument or equipment failure, or fire. The pressure is relieved by allowing the pressurized fluid to flow from an auxiliary passage out of the system. The relief valve is designed or set to open at a predetermined set pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits. When the set pressure is exceeded, the relief valve becomes the "path of least resistance" as the valve is forced open and a portion of the gas or fluid is diverted through an auxiliary route. As the pressure is diverted the pressure inside the vessel should stop rising. Once the pressure lowers and reaches the valves reseating pressure, the valve will close or reseat.

In high pressure gas systems, it is recommended that the outlet of the relief valve is in the open air or relieving to atmosphere.

In some cases a so-called bypass valve acts as a relief valve by by diverting all or part of the fluid (gas or liquid) discharged by a pump or gas compressor back to the inlet of the pump or compressor. This is done to protect the pump or compressor and any associated equipment from excessive pressure. The bypass valve can be internal (an integral part of the pump or compressor) or external (installed as a component in the fluid path).

Technical Terms:

In the petroleum refining, petrochemical, manufacturing, natural gas processing, and power generation industries, the term Relief Valve is associated with the terms Pressure Relief Valve (PRV), Pressure Safety Valve (PSV), and Safety Relief Valve (SRV).

• Pressure Relief Valve (PRV) or Pressure Release Valve (PRV) or Pressure Safety Valve (PSV): The difference is that PSVs have a manual lever to activate the valve in case of emergency. Most PRVs are spring operated. At lower pressures, some use a diaphragm in place of a spring. The oldest PRV designs use a weight to seal the valve.

• Set Pressure: When the system pressure increases to this value, the PRV opens. The accuracy of the set pressure may follow guidelines set by the American Society of Mechanical Engineers (ASME).

• Relief Valve (RV): A valve used on a liquid service, which opens proportionally as the increasing pressure overcomes the spring pressure.

• Safety Valve (SV): Used in gas service. Most SVs are full lift or snap acting. They pop completely open.

• Safety Relief Valve (SRV): A relief valve that can be used for gas or liquid service. However, the set pressure will usually only be accurate for one type of fluid at a time.

• Pilot-Operated Relief Valve (POSRV, PORV, POPRV): A device that relieves by remote command from a pilot valve which is connected to the upstream system pressure.

Inspection Procedure

This procedure applies to all units that are currently in service in the Field, Test Loop, at a Repair Shop, or in Storage Yards. Flogistix Service Technicians will perform the inspection and if needed the replacement of the Pressure Relief Valve as laid out in this procedure.

Before any work is performed, a JSA must be completed in accordance with Flogistix procedure along with any Customer requirements before any work is started.

When visually inspecting pressure relief valves during routine Preventative Maintenance on Flogistix compressor units, the Pressure Relief Valve (PRV) needs to be inspected for any noticeable changes to the PRV as outlined in this procedure.

Step 1: Visually inspect the PRV for any changes to the PRV body for cracks or corrosion.

Step 2: Check the PRV to make sure the data tag is on the PRV body. When checking the data tag, verify that the Set P (pressure) on the data tag of the relief valve does not exceed the Maximum Allowable Working Pressure (MAWP) shown on the data tag on the vessel.

Step 3: Check the PRV to verify that the safety wires are not broken and are sealed together holding the top cover bonnet on the PRV.

Step 4: Make sure piping on outlet of PRV is clear or open preferably to atmosphere. Outlet piping should be pointed upward and may include a weather cap on piping to prevent rain or fluids from getting into PRV outlet. If customer has plumbed the PRV vents to a header, please contact engineering for sizing verification.

Step 5: Make sure there is a drain hole in the lowest point of the PRV outlet piping to be able to drain any fluids that may get in the PRV outlet piping.

If any of the following is found on a PRV, it must be replaced:

• Damage to PRV valve or body is suspected

• Missing data tag

• If the wires or seal of the top bonnet is damaged or broken.

• If PRV has been tampered with or set pressure has been changed.

If replacement of the PRV is required, the same type PRV with the correct set pressure and flow rate must be used for the replacement PRV. If the selection information is not known (such as with a missing data tag), contact Flogistix Engineering for PRV selection.

When replacing a pipe thread mounted PRV, a wrench must be used on the lower hex section of the PRV. A pipe wrench or any other wrench is not to be used on the upper body portion of the PRV housing.

Responsibilities

Management - Management is responsible for implementing, supporting, and enforcing the requirements of this procedure to their respective locations/area.

EHSS - Responsible to assist in the implementation of this procedure and to review for effectiveness.

Employees, Contractors, Vendors, ETC. - Are responsible to follow the follow the requirements outlined in this procedure and ask for assistance

Scope

This procedure applies to all Flogistix compressor skids equipped with Pressure Relief Valves, and are applicable to all Flogistix employees, contractors, and temporary employees.

Hazards

Employees should be aware that units could contain flammable and toxic gasses. Potential for the possible hazards of gas ignition or fire, hot surfaces & fluids, rotating equipment. Risk of possible concentration of H2S. Hazardous gases could be in the units pressure vessels, cooler, or associated piping and risk of inhalation of hazardous gas fumes. Environmental spill of engine waste oil and production fluids

Safety

All Personal Protective Equipment (PPE) for normal Field Mechanical duties apply for this procedure.

Four Gas Monitor, which is outlined in the Flogistix EHSS Manual, PPE Section 8, Procedure 8.3

This procedure applies to all units in service in the field, at a service shop, or in any storage yard.

Insure Flogistix personnel have proper safety certification or site orientation if required by the Flogistix Customer.

Insure Flogistix personnel adhere to all Customers safety practices.

Proper use of required tools

Training

All employees shall be initially trained on the following topics:

• Employee Personal Protective Equipment (PPE)

• Lock Out Tag Out (LOTO) procedure according to Flogistix policy

• Emergency and First Aid procedures

• Methods and Observations that may be used to detect the presence or release of a hazardous chemicals or gas in the work place

Tools & Equipment Required

All employees performing Preventative Maintenance shall be required to have the listed tools to perform job tasks:

• All required PPE according to Flogistix Safety Policy

• Lock Out Tag Out LOTO items to properly perform LOTO procedure according to Flogistix policy

• Basic hand tools

• Pipe wrench and large open end adjustable wrench

Approvals

Field Service approved by: Charles Crenshaw

Date: 4/11/17

Engineering approved by: Aaron Baker

Date: 7/28/17

EHSS approved by: Michael Southard

Date: 09-14-17