Test pressure, piping

Temperature rise, centrifugal pump, 207-209 Terminal particle velocity, 228, 230 Particles, different densities, 238 Single spheres, 274 Solids in air, 237 Solids in water, 237 Test pressure, piping, 18 Thickeners and settleix/decanters, Decanter, 242... 

When constmction is complete, the pipeline must be tested for leaks and strength before being put into service industry code specifies the test procedures. Water is the test fluid of choice for natural gas pipelines, and hydrostatic testing is often carried out beyond the yield strength in order to reHeve secondary stresses added during constmction or to ensure that all defects are found. Industry code limits on the hoop stress control the test pressures, which are also limited by location classification based on population. Hoop stress is calculated from the formula, S = PD/2t, where S is the hoop stress in kPa (psig) P is the internal pressure in kPa (psig), and D and T are the outside pipe diameter and nominal wall thickness, respectively, in mm (in.). 

The code prescribes minimum requirements for the materials, design, fabrication, assembly, support, erection, examination, inspection, and testing of piping systems subject to pressure or vacuum. The scope of the piping covered by B31.3 is illustrated in Fig. 10-124. It applies to all fluids including fluidized sohds and to all seivdces except as noted in the figure. 

Standard Test Pipe Test Gas Stable Detona- tion Over- driven Detona- tion Deflagra- tions Test Pressure Endur- ance Burn Test... 

A workman, who was pressure testing some pipe work with a hand operated hydraulic pump, told his foreman that he could not get the gauge reading above 200 psi. The foreman told him to pump harder. He did so, and burst the pipeline. The gauge he was using was calibrated in atmospheres and not psi. The abbreviation "atm." was in small letters, and in any case the workman did not know what it meant. 

Safety as it is reflected in factors of safety in design of pressure vessels, pressure testing of piping and vessels, etc. Use of A.P.I., A.S.M.E. and ASA Codes Code Stamps on equipment. 

Pipework and other components should be insulated after the safety pressure test, but usually before prolonged running of the plant, since it is very difficult to remove water and frost once it has formed. Only the low-pressure piping is insulated, where it does not form part of the evaporator, i.e. after the expansion valve, where this may be outside the cooled space, and from the evaporator back to the compressor. Basic materials are cork and the expanded plastics. These are sufficiently rigid to be moulded to the correct shape, remain firmly in place, and support the external vapour barrier which is essential to prevent the ingress of water vapour (see also Chapter 15). 

If operation pressure is greater than 150 psi, test pressure to be 50 psi above operational pressure. Limited to hoses and agent containers Note 3 Piping not to be hydrostatically tested. 

Hydrostatic test pressure (TP) shall be limited to the pressure calculated per para. IP-10.7.2. The maximum testing interval shall be 10 years. Inline examination is normally applied to pipelines or buried piping specifically designed for this type of assessment and should be a requirement for piping systems only when the piping is specifically designed for inline examination. 

For a liquid thermal expansion relief device that protects only a blocked-in portion of a piping system, the set pressure shall not exceed the lesser of the system test pressure or 120% of design pressure. 

A piping system containing expansion joints shall be leak tested without temporary joint or anchor restraint at the lesser of 150% of design pressure for a bellows-type expansion joint or the system test pressure determined in accordance with para. IP-10.6. In no case shall a bellows-type expansion joint be subjected to a test pressure greater than the manufacturer s test pressure. 

Equipment that will not be tested shall be either disconnected from the piping or isolated by blinds or other means during the test. A valve may be used, provided the valve (including its closure mechanism) is suitable for the test pressure. 

Except as provided in para. IP-10.7.3, the hydrostatic test pressure at any point in a metallic piping system... 

Limitations on Design Pressure, P, in Para. PL-3.7.1 (a). The design pressure obtained by the formula in para. PL-3.7.1(a) shall be reduced to conform to the following P shall not exceed 85% of the mill test pressure for all pipes in the pipeline, provided, however, that pipe, mill tested to a pressure less than 85% of the pressure required to produce a hoop stress equal to the specified minimum yield, may be retested with a mill type hydrostatic test or tested in place after installation. In the event the pipe is retested to a pressure in excess of the mill test pressure, then P shall not exceed 85% of the retest pressure rather than the initial mill test pressure. It is mandatory to use a liquid as the test medium in all tests in place after installation where the test pressure exceeds the mill test pressure. This paragraph is not to be construed to allow an operating pressure or design pressure in excess of that provided for by para. PL-3.7.1(a). 

The design pressure of the test heads and piping, and the rated pressure of hoses and valves in the test manifold, shall be no less than the anticipated test pressure. All equipment should be inspected prior to the test to determine that it is in satisfactory condition. 

The development of medium and high density polyethylene pressure pipes over the last thirty years has led to an extensive database on their stress-rupture behaviour, with associated standards for their testing and the interpretation of results [1, 2], Various forms of PVC are also used. The accelerated testing of gas and water pipes is introduced as an example of a field where there is a large database of pressure testing on which current regulations are based, the number of polymers is limited and accelerated tests are widely used (unusually, with two accelerating parameters). 

ISO 1872-1 1993 Plastics - Polyethylene (PE) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 1872-2 1997 Plastics - Polyethylene (PE) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 1969 2004 Fibre ropes - Polyethylene - 3- and 4-strand ropes ISO 3458 1976 Assembled joints between fittings and polyethylene (PE) pressure pipes -Test of leakproofness under internal pressure ISO 3459 1976 Polyethylene (PE) pressure pipes - Joints assembled with mechanical fittings - Internal under-pressure test method and requirement ISO 3501 1976 Assembled joints between fittings and polyethylene (PE) pressure pipes -Test of resistance to pull out... 

ISO 3503 1976 Assembled joints between fittings and polyethylene (PE) pressure pipes -Test of leakproofness under internal pressure when subjected to bending ISO 3663 1976 Polyethylene (PE) pressure pipes and fittings, metric series - Dimensions... 

ISO 8796 2004 Polyethylene PE 32 and PE 40 pipes for irrigation laterals - Susceptibility to environmental stress cracking induced by insert-type fittings - Test method and requirements ISO 9625 1993 Mechanical joint fittings for use with polyethylene pressure pipes for irrigation purposes... 

ISO 14236 2000 Plastics pipes and fittings - Mechanical-joint compression fittings for use with polyethylene pressure pipes in water supply systems ISO 14616 1997 Plastics - Heatshrinkable films of polyethylene, ethylene copolymers and their mixtures - Determination of shrinkage stress and contraction stress ISO 14632 1998 Extruded sheets of polyethylene (PE-HD) - Requirements and test methods... 

ISO 3603 1977 Fittings for unplasticized polyvinyl chloride (PVC) pressure pipes with elastic sealing ring type joints - Pressure test for leakproofness ISO 3604 1976 Fittings for unplasticized polyvinyl chloride (PVC) pressure pipes with elastic sealing ring type joints - Pressure test for leakproofness under conditions of external hydraulic pressure... 

ISO 8361-2 1991 Thermoplastics pipes and fittings - Water absorption - Part 2 Test conditions for unplasticized poly(vinyl chloride) (PVC-U) pipes and fittings ISO 9393-2 1997 Thermoplastics valves - Pressure test methods and requirements - Part 2 Test conditions and basic requirements for PE, PP, PVC-U and PVDF valves ISO 9852 1995 Unplasticized poly(vinyl chloride) (PVC-U) pipes - Dichloromethane resistance at specified temperature (DCMT) - Test method ISO 9853 1991 Injection-moulded unplasticized poly(vinyl chloride) (PVC-U) fittings for pressure pipe systems - Crushing test... 

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