International Standard Safety Practices for Pressure Testing

1 Introduction

Pressure testing is a common industrial procedure carried out in all process industries. It is a procedure conducted to ensure that piping and vessel systems can safely operate at the design parameters. High-pressure operations involve a high level of risk, and it is pertinent to carry out all the safety procedures before conducting the pressure testing. Before any pressure testing is carried out, a systematic inspection is required to make the procedure hazard free and safe for operation. For industry-standard safe practices for pressure testing, a dedicated safety officer decides the parameters required. This document highlights all the industry-standard safety practices involved in pressure testing procedures.

2 Scope of the article

This article is applied to all the operations involved in the safety practice.

3 Types of Pressure Testing Carried out in the industries

Hydrostatic Testing: usually, the preferred method of testing is hydrostatic testing, as it involves less stored energy and carries less potential of hazard. In hydrostatic testing, water at low pressure is pumped into the system, and no air is used. This reduced the overall stored energy of the system.

Pneumatic testing: this type must be used only when hydrostatic testing cannot be performed in the system. As the stored energy in pneumatic testing is very high, it has a great potential for hazard. As water cannot be compressed in hydrostatic testing, pneumatic testing causes air compression at high pressures making it highly dangerous for workers.

4 Pressure Testing Safety

In pressure testing, most of the hazards are associated with the sudden release of the stored energy in the system. As the system contains joints, valves, gauges, and other components, the free fall or release of these components with high pressure can result in a potential hazard at the workplace. This intends a safe workplace environment for pressure testing procedures.

5 Knowing the Pressure Testing Hazards

Following pressure testing hazards are involved in the pressure testing practices:

1. Free falling or flying industrial parts such as valves, joints, gauges etc.
2. Due to high pressure, free-falling or flying sharp objects like pipe cuttings and fittings are caused.
3. Decrease in the oxygen values at the pressure testing site involving the use of inert gas.
4. Flooding in an electrically active site where hydrostatic testing is being performed.

6 Common injuries that occur at the pressure testing locations

The following are the most frequently registered injuries involved in the pressure testing sites:

1. Damage to the eyes.
2. Ruptured skin.
3. Laceration
4. Fractured bones.
5. Internal injury
6. Concussions
7. Contusion

Less common but other possible injuries at the pressure testing sites are:

1. Asphyxiation results from the reduction in the amount of oxygen present at the worksite. This is due to the use of inert gas during pressure testing procedures. These gases are usually nitrogen or argon.
2. Electrocution is an area where hydrostatic testing is being performed.

The above-discussed injuries are inevitable if the Standard Operating Procedures (SOPs) for the safety of workers is not performed. In addition, safety training of the workers and careful implementation of safe practices are important to avoid any injury.

7 Pressure testing failures usually occurred during the process

Following are the common failures that occur during the pressure testing procedures:

1. System over pressurising
2. Lack of proper pressure testing equipment
3. Loopholes in the design of the pressure testing system
4. Human error
5. Improper repairing in the system
6. Failure to segregate the area in which pressure testing is being performed.

8 Addressing the common failures occurring in the pressure testing procedures

Over pressurised systems: to control the over pressurising of the system, it must be first tested with a test pressure. The safety engineer studies the design pressure first to know the maximum pressure the system can be tested. Many parts of the system, including valves, gauges, pipe fittings and others, can withstand a limited amount of pressure. The system designers already provide the design pressure of the system and its components in the process manual. These manuals should be frequently referred to during pressure testing procedures. The Safety and process engineers must perform the following calculations.

• Calculate the test pressure and time required for testing.
• Installation of a pressure relief valve to avoid over pressurising the system.
• Avoid rapid increases in the pressure of the system.
• Pressure must not increase beyond the test pressure.

Lack of proper pressure testing equipment: valves, gauges, pipes, hoses and pipe fitting are the usual pressure testing equipment involved in the pressure testing procedures. Test equipment can fail during the procedure if low quality and cannot design at high pressures. In addition to its proper calibration of the equipment is also important. Following steps can be taken to avoid safety hazards:

• Use of manufacturer guaranteed and tested pressure testing equipment.
• Use of latest manuals provided by the manufacturer to ensure that equipment specifications are properly followed.
• Calibration of all the test equipment, including all the test gauges, at least within one year of the use.
• Checking and replacing all the damaged parts of the system, including gauges that do not register zero.
• During the test procedure, all the gauges must be visible to the operator to monitor the pressure values properly.

Loopholes in the design of the pressure testing system: Possible loopholes in the system design can affect the system’s operation. This also included improper functioning of the part of the system. Mostly system failure occurs due to design errors failing the system components.

To avoid this, it is important to verify the system before commissioning. It is also necessary to cross-check the original design data before initiating the pressure test.

Human error is the most anticipated error in the pressure testing process. It usually occurs when the operators rush towards the test without performing the necessary checklist. Operators also fail to follow the standard operating procedures of the pressure testing, the process guidelines and equipment specification list.

To avoid this, the following procedure must be followed:

1. Following all the SOPs written in the safety manual of the process.
2. Inclusion of the process and safety workers in the safety and planning process workshops.
3. Ensuring strict health and safety supervision of the process by dedicated safety officers.

Improper repairing in the system: Error in the repair system before the pressure testing or modification of the existing process can cause problems in the pressure testing procedure. For example, improper fittings misaligned or ruptured gaskets can cause pressure failure in the system. To avoid this, the following measures must be taken:

1. Inspection of all the parts of the process, especially repaired or modified before the pressure test.
2. Following all the international standards of the operation during the pressure testing process.

Failure to segregate the area in which pressure testing is being performed: It is important to isolate all the parts of the system involved in the pressure testing. If the system is not isolated, it can affect other system parts that are not under test. As a precedent, if a relief valve not included in the pressure test is not isolated, high pressure can fail the valve leading to damage to the entire system. Moreover, high pressure can shatter the components of the system and cause hazardous conditions for the workers involved in the pressure testing procedure. To avoid this, the following precautions must be taken:

1. Draft and review the pre-test safety plan and conduct planning exercises before the test.
2. Ensure that all the SOPs are followed during the pressure testing procedure.
3. Presence a checklist during the procedure to ensure all the SOPs are properly executed.

9 Hydrostatic Testing Safe Work Practices

Ensuring the Standard Operating Procedures:

Apart from this document, all the ASME standards should be followed in the SOPs during hydrostatic testing.

1. The use of this Safe Work Practices document must be ensured and the ASME standards. This is a critical step before the pressure testing procedure.

10 Defining the checklist

Use of all the SOPs defined for the hydrostatic pressure testing.

11 Pre-Test Safety Plan

The safety engineer must draft a pre-test safety plan based on the defined SOPs for hydrostatic testing. This pre-test safety plan must include the following:

1. Incorporate all the workers involved in the test, the stakeholders of the company, and planning process authorities.
2. Listing all the possible hazards involved in the pressure testing process and their impacts on the workers involved in the test.

12 Training of the workers

All the workers involved in the process must be trained for hydrostatic tests and the specifications involved in the test.

1. Make sure all the SOPs are followed in the checklist.
2. Ensure that all the workers thoroughly understand the possible hazards involved in the hydrostatic testing process.

13 Safety Briefing to the Workers

Before initiating the safety process, the workers should be briefed about the test:

1. Review the pre-test plans
2. Make sure that all the workers completely understand the entire process of the testing procedure.
3. Ensure that the workers have all the required equipment, safety materials, PPEs, for hydrostatic testing.
4. Presence of two-way communication during the entire testing procedure.
5. Making an emergency response plan (ERP) in case of any hazardous condition in the development.

14 Walk down procedure

Before starting the pressure testing, process and safety engineers should perform a walk-down procedure to inspect the system physically. At this stage, the safety checklist is important.

1. All the important equipment must be identified and cross-checked to rule out equipment failure.
2. Ensure system isolation is involved in the pressure test.
3. It must be ensured that pressure vents are available and pneumatic bleeding is present.
4. Inspection of all the joints and valves in the system. Moreover, all the insulations must be removed.
5. Replacing/removing the damaged components of the system before starting the pressure test.
6. All the tagout procedures are to be performed correctly.

15 Final Test Checklist

The final test checklist must be carefully prepared in light of the following points:

1. Replace all the required components before the test.
2. Remove all the air pockets in the system and close all the necessary valves.
3. Cross-check the design and safety pressure.
4. Ensuring the calibration of all the gauges involved in the test. Zero registration is important.
5. Ensure that all the gauges are visible to the reader.
6. Ensure that the metal temperature is normal.
7. Use red tape to mark the area under test to help human isolation from critical points.
8. Use of HSE signs to ensure everyone follows the required safety SOPs.
9. Isolating the entire test area from unauthorised personnel.
10. All the personnel at the worksite must be informed about the initiation of the test procedure.

16 Use of Personal Protective Equipment

Before initiating the process, the use of PPEs by every person involved in the test must be ensured. In the pressure testing process, the following PPEs must be used.

1. Hardhat
2. Safety Glasses
3. Gloves
4. Face shields
5. Hearing protection

17  Final Testing

The following SOPs must be followed during the pressure testing procedure:

1. Increase the pressure gradually to check the system’s response to the test.
2. Do not apply the pressure beyond the allowable pressure designed for the system or a single component. The ASME pressure testing procedures must be followed apart from this document.
3. The pressure applied must not be more than 1.5 times the designed pressure in case of hydrostatic testing.
4. It is important to maintain the hydrostatic test pressure above the recommended level for at least 10 minutes before reducing it to the design pressure.
5. All the joints and connecting must be continuously monitored during the test procedure.

18 Post Test Inspection

After the test is successfully conducted, a post-test inspection is necessary. The following procedure must be ensured:

1. If any repair is needed, the pressure must be released before the repair is initiated.
2. The system should be thoroughly drained.
3. All the liquids used must be disposed of.
4. All the system components must be repaired.

19 Pneumatic Testing Safe Work Practices

Ensuring the Standard Operating Procedures:

1. A pneumatic test permit must be obtained.
2. Use of safe work practices as written in the ASME guidelines.

20 Pre-Test Safety Plan

Use the same pre-test safety plan as listed in the hydrostatic testing.

21 Permit Approval

Work permit for Pneumatic testing must be obtained from the safety supervisor.

22 Training of the workers

Use the same training plan as listed in the hydrostatic testing.

23 Safety Briefing to the Workers

Use the same safety briefing as listed in the hydrostatic testing.

24 Walk down procedure

Use the same walk down procedure as listed in the hydrostatic testing.

25 Final Test Checklist

Use the same final test checklist as listed in the hydrostatic testing.

26 Use of Personal Protective Equipment

Before initiating the process, the use of PPEs by every person involved in the test must be ensured. In the pressure testing process, the following PPEs must be used.

1. Hardhat
2. Safety Glasses
3. Gloves
4. Face shields
5. Hearing protection

27 Final Testing

The following SOPs must be followed during the pressure testing procedure:

1. Increase the pressure gradually in light of ASME standards and SOPs defined to check the system’s response to the test.
2. Do not reduce the pressure below 100 psig or the design pressure, whichever is lower.
3. Carefully monitor the system leaks.
4. The use of liquid leak detectors must be ensured.
5. Do not apply the pressure beyond the allowable pressure designed for the system or a single component. The ASME pressure testing procedures must be followed apart from this document.
6. The pressure applied must not be more than 1.5 times the designed pressure in case of hydrostatic testing.
7. It is important to maintain the hydrostatic test pressure above the recommended level for at least 10 minutes before reducing it to the design pressure.
8. All the joints and connecting must be continuously monitored during the test procedure.

28 Post Test Inspection

After the test is successfully conducted, a post-test inspection is necessary. The following procedure must be ensured:

1. If any repair is needed, the pressure must be released before the repair is initiated.
2. The system should be thoroughly drained.
3. All the liquids used must be disposed of.
4. All the system components must be repaired.
5. Retest the system if required.

29 Supervisor Responsibilities:

The supervisor is responsible for the following acts:

1. Training of all the workers involved in the test.
2. Ensure that all the safety tools are present at the site required during the test.
3. All the work permits are taken.
4. All the process checklists are present.
5. The area is completely isolated.
6. All the required workers are present at the site.
7. Each hazard is reviewed and identified.

30 References

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