Pressure Testing Safely Training

PRESSURE TESTING SAFETY TRAINING

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OVERVIEW & PURPOSE:

This training is made to ensure that working personnel involved in HIGH-PRESSURE SYSTEM testing have knowledge of the hazards and dangers associated with the said activity.

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Objectives

OBJECTIVES:

1. By the end of this session, participants will know the definition of hydrotesting and the difference to other testing conducted on site.
2. In the end of the training, participants will have an idea regarding the purpose in line with the other construction activities.
3. This training will ensure that attendees will be able to recognize the hazards of hydrotesting activities
4. By the end of this training participants will remember the safety precautions they need to establish to avoid injuries related to the known hazards.
5. Through this training, participants will also be able to know the DO’s and DON’TS of hydrotesting activities.
6. By the end of this training the attendees will able to apply the safety measures to be discuss in the course as part of their duties assigned as a hydrotesting involved personnel.

Definition

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HYDROTESTING DEFINITION:

1. The hydro test is the test that is carried out by using water. Water is pressured using the hand/engine pump to a certain pressure and has to put the system on hold for some time to observe any leak or failure. If it falls after achieving the required pressure, it means having some problems in the system.
2. Hydrostatic testing involves filling the vessels, pipeline, or system (which need to be tested) with water, then pressurizing with a hydraulic pump until the test pressure reaches (normally 1.5 times design pressure), holding the pressure for a specified time by shutting off the supply valve and checking for any leakage or pressure drop. If the pressure drops beyond the standard tolerable limit, the test is declared FAILED.

Incident Case #01

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Safe connection

INCIDENT CASE #01:

Emptying of a Vertical Tank

• While the tank was being emptied, it suddenly collapsed. Root cause analysis shows that a plastic sheet that was protecting the roof was trapped in the vent which created a vacuum.
• So it is a must to inspect the venting systems before filling and emptying operations. There was no injury. It should be noted that this type of incident is not that unusual.

Incident Case #02

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INCIDENT CASE #02:

Hydrotest of a New Vertical Vessel

• The image shows an exploded vessel that happened during hydro testing of a new vessel. The root cause of the incident is not known fully. But there was some brainstorming and people thought that hydro-testing with “very cold” water could be a contributing factor. The good news is that no injuries occurred.
• Learning from the Incident It is learned that water temperature during hydro testing is critical. It is suggested to maintain the metal and water temperature at least at 16°C or at least 10°C above the impact test temperature of the metal during pressure testing.

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Incident Case #03

INCIDENT CASE #03:

Water Filling of a New Vertical Tank

• This incident happened while filling the tank with water from a fire hydrant. As the relief valve could not displace the air fast enough for the volume of water that was being pumped in, The top of the tank blew off suddenly.
• Fortunately, no injury happened, but an operator was on top of the tank a few seconds before.
• Top of tank blew off during hydrotesting

Incident Case #04

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INCIDENT CASE #04:

Sphere Tank Collapse During Hydrotesting

• During the filling of a 2000 m3 LPG sphere, Its legs suddenly collapsed. One nearby person was killed and one was seriously injured. The research found that the sphere was approximately 80% full of fresh water. The vessel’s last hydro test was 10 years ago and the last inspection of its legs was done 5 years ago. The main cause was the Severe corrosion of the legs under the concrete fire protection. The corrosion occurred due to water ingress between the concrete and the steel legs. The water protective cap that was located over the concrete was not sufficient to keep the water out. It was verified later that the steel legs had its thickness reduced by up to 8 mm, with pitting holes of up to 10cm2.

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INCIDENT CASE #04:

Sphere Tank Collapse During Hydrotesting

• Thorough investigation and tests confirmed that the following factors contributed to the sphere collapse:

1. Poor design of the water caps over the fire-proofing concrete was allowing the water to penetrate the steel beams and the concrete. 2. Vertical cracks in the concrete let water in. 3. Poor workmanship during Repairs had been done to the concrete. 4. The new concrete had not adhered to the old concrete, again letting water in. 5. The deluge system had been tested with saltwater, increasing the possibility of corrosion.

• Learning from the incident A complete inspection must be performed visually and if required with NDT before pressure testing of an old vessel. This inspection must include the vessel, nozzles, appurtenances, and supporting structures.

Testing Purpose

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PRESSURE TESTING PURPOSE:

• Identify the leaks.
• To check the strength of the welded joint.

• To check the capacity of the system.
• To complete it SAFELY.

Testing Hazards

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HYDROTESTING HAZARDS:

• Inadvertently/suddenly increase of pressure due to underrated or non-calibrated pressure gauges.
• Substandard support.
• PSV failure.

• Breaking/failure of line, gasket, flanges, and

gauges.

• Air entrapment inside the pipe.
• Usage of an engine operated pump.

Safety Measures

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HYDROTESTING SAFETY MEASURES:

Hydrostatic testing is a risky process as it involves pressurizing the system with high pressure which can fail and cause serious personal injury or property damage. Although testing is performed under the supervision of a competent person, the following is the risk associated with hydrostatic testing;

In the event of a leak or burst, a person can be injured by exposure to high pressure liquid. High pressure fluid can tear the skin and damage internal organs.

The pressure hose connection of hydraulic pump to test piping/ vessels can be detached and may hit a person nearby.

Training Video

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INCIDENT VIDEOS

INCIDENT VIDEOS

To control the above hazards, appropriate safety precautions must be ensured while performing pressure testing.

• The hydrostatic test must only be performed under the supervision of a competent person.
• Only essential and trained persons shall be allowed at the pressure test work location.
• Follow the permit to work system and establish communication.
• Barricade the area to restrict the man movement and display caution boards to alert people.
• Provide whip latch arrester to secure the hoses connection.
• Equipment and accessories used for pressure build-up and inspections must be certified and calibrated.
• Calibrated pressure gauges and Pressure safety valves only shall be used.
• Rating of fittings, pressure gauges, vent valves, gaskets shall be suitable for the test pressure.
• Flanges and Plates shall be as per the line class.

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• All the temporary welding shall be performed by qualified welders and approved by Client QA/QC.
• Ensure air vent provided at the highest elevation.
• Gradual filling of lines shall be done keeping vent to open.
• Ensure that the line is vented to remove air pockets before pressurization.
• Pressure should be raised gradually under control to allow time for pipes to strain and time for personnel to check for leaks.
• There shall be at least two pressure gauges, one at lowest point and another at the highest point in the system.
• Pressure testing crew should not stay in the direction of the blind flanges to prevent injury in case of flange rapture.
• All hoses/ piping/gaskets and connectors/clamps shall be of adequate rating to withstand pressure.
• Personnel shall not approach the system under high Pressure.
• Access shall be free from any obstacle.
• Supervisors shall be present at work location during hydro testing activities are done.
• Risk assessment shall be done for any pressure testing job.

DO's

• Follow the permit to work system and communicate the associated hazards to engaged manpower.
• Perform hydrostatic test under the supervision of a competent person only.
• Clearly mark the scope of hydrotest on P&ID and ensure positive isolation of equipment and piping that are not included in the hydrostatic test loop.
• Inspect all test equipment and tools, even if they are brand new. Check the design pressure of equipment such as vessel, piping, etc. before the test.
• Ensure calibration of pressure measuring instruments and tools.
• All fittings must be rated above the maximum hydrostatic pressure. *Ensure the setting and calibration of safety relief valve.
• Install at least two pressure gauges at an appropriate place so that it is easily readable.
• Isolate, barricade the test area with safety signage in local and English language.
• If possible, perform the test from a remote area. Make sure that all pipeline and vessel supports are firm, in good condition and have been inspected prior to start hydrotest.
• Start the de-pressurization by gradually opening the vent valve. Open the lowest drain point to remove water from the vessel, pipeline, etc.
• Always wear appropriate personal protective equipment (PPEs).

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Testing Failures

DON'TS

• Don’t monitor the pressurization step directly in front of the pressure gauges.
• Don’t forget to remove the air pockets through the vent line.
• Don’t attempt to tighten the bolts if the flange leaks during hydrotesting and system is pressurized.
• Don’t open the drain valve if the vent valve is closed. *Don’t use a pressure gauge with under rated capacity. *Don’t allow unauthorized person to enter the test area.
• Don’t forget to obtain work permit and wear appropriate PPEs.
• Don’t leave any electrical equipment without adequate protection
• Don’t leave the remaining/ residual pressure trapped inside the pipeline or vessel after testing.
• Don’t forget to provide proper access and egress for work at height.
• Don’t drain the hydrotest water on the floor, make sure there is adequate drainage.
• Don’t miss to isolate monitoring devices/ site glass. *Don’t allow other activities in the vicinity of the hydrotesting work area.

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Testing Failures

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Pressure Vessel Failure During Air Test

Pneumatic Test Incident Jan 26 2006..accident occurred in a factory in Brazil, during pneumatic pressure testing with Air from pipe work around a tank. There were no blind flanges are placed in order to isolate the pipe work to the tank, only the valves were closed. Probably has one or more valves failed, or were not closed, and the tank also has undergone a pressure test. As a result, there has been a tremendous energy built up in the tank, and the tank launched and ended up on top of the installation.

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Calculating SaFE DISTANCE FOR PRESSURE TESTING SAFE DISTANCE = (0.15) x (D) x (A) / 0.4 x (P) / 0.6 (D) - INTERNAL PIPE DIAMETER (A) - LENGHT/DIAMETER OF THE PIECE (P) - TEST PRESSURE (BAR)

https://hsseworld.com/pressure-testing-and-safe-distance-calculation/

https://www.piping-world.com/safe-distance-and-stored-energy-calculator-pneumatic-test

THANK YOU!