THEORY OF HYDRO TEST

HYDRO TEST

》Definition:- It is a process where components such as piping system gas cylinder, Boiler, and Pressure vessels are tested for strength and leakage.

》Test fluid:-There are various term related as :

• Ph Value of water → 5.5 to 8.0

• Sulphur Reducing Bacteria (SBR) → Greater than 10 square per million.

• For Carbon Steel chloride value → Less than 200 ppm.

• For Stainless Steel chloride value → Less than 50 ppm.

• Note- If chloride value is doesn't maintain then Pipe can be corrosion.

•  Hydrostatic pressure: not more than 1.5 times the design pressure. 

》Arrangement of Equipment for hydro test:-

1. Water (Ph value should be between 5.5 to 8.0).
2. Hydro test pump:- Hydro test pumps are common procedure used to check fluid pressure vessel, such as cylinders, Boiler, tube, Pipe, valve, casting, components etc. (PUMP- The pump converts rotational motion into fluid flow).

HYDRO TEST PUMP

     3. Pressure Gauge :- (This should be 2 piece for drain point and vent point)- It's an instrument for measuring the condition of fluid (Liquid or Gas).

PRESSURE GAUGE

     4. Fittings:- (Valve, Reducer, Nipple, Union etc).

• Pipe Nipple- Nipple is a short stub of pipe which has a male pipe thread at each end or at one end. It used for connecting two other fittings. Nipples are used for connecting pipe, hoses, and valves. Pipe nipples are used in low-pressure piping.

• Union- Union joins screwed and socket weld pipe and male connection. When they may need to be broken apart in the future, the union is possible leak joint and should be used where the break away future is necessary.

 

PIPE UNION

•  Reducer- A pipe reducer changes the size of the pipe. There are two types of reducer used in piping Concentric & Eccentric.

1. Concentric Reducer or Conical Reducer- It is also known as Conical Reducer, where are used in pump discharge for liquid (vertical pipelines etc).

Concentric Reducer

 2. Eccentric Reducer- It is used in pump suction to avoid cavitation, To maintain elevation Bottom of Pipe (BOP) in rack.

ECCENTRIC REDUCER

Note:- Concentric Reducer can never use in pump suction. Because pump can be corrosion.

Installation assembly Eccentric reducer at pump side

• Valve- A part attached to a pipe or tube, it can be used to control the flow of liquid, gases and  slurries. 

  

A. Pressure Safety Valve :- Usually it is fitted where pressure rise gradually, Directly open at set pressure and can be operated manually. (Example- On boiler steam drum and on air bottle).

Pressure Safety Valve

B. Pressure Relief valve :-  Usually it is fitted where pressure raises rapidly, Opening and closing is proportional to pressure rise, Can't be operated manually (Example- on delivery side of air compressor, on delivery side of positive displacement pump).

PRESSURE RELIEF VALVE

     5. TEST MANIFOLD :- A manifold which can be hired out individually or with a pump for testing pressure between 1000 and 3000 psi. Pump hose connects at one end and the other connects to the pipe. (Manifold pressure: at least 1.2 times the system pressure but not less than discharge pressure of pump used for pressure testing).

Test Manifold

DOCUMENTS REQUIRED TO HYDRO TEST PACKAGE:- 

There are various documents required for hydro test package- 

1. Table contents
2. Safety instruction sheet for critical services
3. Flow chart of test package
4. Pre-test Punch list 

• Test procedure & Pressure test diagram
• Related P&ID and Isometric Drawings
• Line List
• Pre-Test Punch List Checklist I Form

 5. QA/QC Documentation of the system to be tested.

• Weld inspection summary sheet

• Weld map

• Non-Destructive Examination records

• As- built Drawings

• Isolation Valve Test Certificates

• Flange Joint Inspection Report

• Internal Cleanliness I flushing Report.

  6. Pressure Testing.

• Verification of Temporary Gaskets

• Verification of  Test blind rating

• Checklist for Verification of system readiness for Testing

• Calibration certificates for Pressure gauge & Pressure Safety Valve

• Calibration Certificates for Pressure & Temperature recorders

• Test Manifold Certificate

• Water Analysis (test medium) 

• Pressure Test report Form 

• System Lay-up certificate

• Re-reinstatement or Final Assembly Inspection (Final Punch List).

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