Hydrostatic test

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 variatioa of average pipeline coastmctioa costs with increasing size of line pipe is showa ia Figure 2, based oa data takea from FERC coastmctioa permit appHcatioas from July 1991 to July 1992. The cost of a common carrier pipeline project must be reported to the FERC ao later than six months after successful hydrostatic testing. 

The hydrostatic-test pressure at any point in the system shall be as follows ... 

A preliminaiy air test at not more than 0.17-MPa (25-lbf iu ) gauge pressure may be made prior to hydrostatic test in order to locate major leaks. 

If hydrostatic testing is not considered practicable by the owner, a pneumatic test in accordance with the following procedure may be substituted, using air or another nonflammable gas. 

The hydrostatic test is, in one sense, a method of examination of a vessel. It can reveal gross flaws, inadequate design, and flange leaks. Many beheve that a hydrostatic test guarantees the safety of a vessel. This is not necessarily so. A vessel that has passed a hydrostatic test is probably safer than one that has not been tested. It can, however, stiU fail in service, even on the next appheation of pressure. Care in material selection, examination, and fabrication do more to guarantee vessel integrity than the hydrostatic test. 

The ASME Codes recommend that hydrostatic tests be run at a temperature that is usually above the nil-ductility temperature of the material. This is, in effect, a pressure-temperature treatment of the vessel. When tested in the relatively ductile condition above the nil-ductihty temperature, the material will yield at the tips of cracks and flaws and at points of high residual weld stress. This procedure will... 

It is possible to design a hydrostatic test in such a way that it probably will be a proof test of the vessel. This usually requires, among other things, that the test be run at a temperature as low as and preferably lower than the minimum operating temperature of the vessel. Proof tests of this type are run on vessels built of ultrahigh-strength steel to operate at cryogenic temperatures. 

Among the available nondestructive testing techniques are ultrasonic tests, eddy-current tests, air-underwater and hydrostatic tests, and visual examinations. All of these techniques must be executed by technically qualified personnel. 

Each test has specific limitations and may pass defects of various sizes and orientations. The specific limitations for a particular technique must be understood for correct interpretation of results. For example, hydrostatic tests and air-underwater tests may pass defects that run 70% of the wall thickness. Hydrostatic tests may pressurize a defect in such a way that leaking does not occur in the test but can in service. 

If a design limit test is included in the test run (such as a hydrostatic test) and it exceeds safe operating limits, consider writing a special procedure for this part of the test. 

Cleanliness Hardness Hydrostatic Tests Blade Shaker (Static) Rotor balance O Standard O High Speed Final Surface Inspection Crating inspection Spare Rotor Fit ... 

The turbine undergoes three basic tests, these are hydrostatic, mechanical, and performance. Hydrostatic tests are to be conducted on pressure-containing parts with water at least one-and-a-half times the maximum operating pressure. The mechanical run tests are to be conducted for at least a period of four hours at maximum continuous speed. This test is usually done at no-load conditions. It checks out the bearing performance and vibration levels as well as overall mechanical operability. It is suggested that the user have a representative at this test to tape record as much of the data as possible. The data are helpful in further evaluation of the unit or can be used as base-line data. Performance tests should be conducted at maximum power with normal fuel composition. The tests should be conducted in accordance with ASME PTC-22, which is described in more detail in Chapter 20. 

Operator training was planned to take place four months prior to the first heat-up. Half of the operators were to be on the payroll five months, and the other half for three months. As part of the training, each operator was to have spent four weeks in the plant inspecting construction, becoming familiar with the equipment, and helping with hydrostatic testing and internal cleaning. 

The word lest is quite broad in its definition, and many of the inspection steps in the course of the compressor manufacturing cycle can appropriately be called tests. An example would be the material tests. The API mechanical equipment standards, however, attempt to narrow the test definition. This chapter will discuss testing within these narrowed definitions. The first test defined in most API mechanical equipment standards is the hydrostatic test, and it will, therefore, be the first test covered in the chapter. 

When the seal maximum pressure is such that the gas test must be conducted well below rated discharge pressure, then another test, or substituted test, may be invoked in which the seals are removed. It may require removing the rotor however, with this procedure the joint makeup still remains a problem when the rotor is replaced. However, without the seals, the test described earlier is performed, using the rated discharge pressure rather than the maximum seal pressure. The acceptance test is the same also no leaks should be detected. The latter test should help to still controversy about minor joint leaks on a hydrostatic test, if the casing is proven at rated pressure on gas. 

The hydrostatic testing is the first test used on the lube system. The system is tested while assembled or partially assembled, based on the particular system. A test pressure of VA times the maximum allowable working pressure, a minimum of 20 psi for the oil side, is used for the test. For the oil-wetted parts, the test fluid should be light oil, which is normally the recommended lubricant for the compressor train. The test period is the length of time needed to inspect for leaks, or a minimum ol thirty minutes. Acceptance is based on the lack of leaks as visually observed or the lack of a drop in the test pressure. 

A certain number of the tests will have been designated as witness tests. One is usually the hydrostatic test, which does not require an engineer but can be witnessed by an inspector. As a cost-saving measure, if engineers from another project happen to be in the plant at the time of the hydrostatic test, they may be able to arrange to witness the test, because the duration of the test is normally not long. It may take a total of two hours. 

Hori/miully iplit ccmntugal, 134 HohlIcii t otnpany, 95 Humidity, 20 Hunting tooth design, 330 Hydraulic hub removal, 335 Hydrostatic testing, 405... 

Objectives, Hydrostatic Test. Impeller Overspeed Test. 

All pressure vessels must pass appropriate hydrostatic testing before approval for service. For safety reasons, hydrostatic pressure testing is almost always recommended over a pneumatic test. The recommended... 

In some cases where the ASME Code woidd not require pressure relief protection, the 1.5 Times Design Pressure Rule is apphcable. This rule is stated as follows Equipment may be considered to be adequately protected against overpressure from certain low-probability situations if the pressure does not exceed 1.5 times design pressure. This criterion has been selected since it generally does not exceed yield stress, and most Ukety would not occur more frequently than a hydrostatic test. Thus, it will protect against the possibility of a catastrophic failure. This rule is applied in special situations which have a low probability of occurrence but which cannot be completely ruled out. 

The detonation arrester mnst be hydrostatically tested to 350 psig for 10 minntes, withont mptnre, leakage, or permanent distortion. 

The deflagration flame arrester must be hydrostatically tested to 250 psig for one minute without rupture or permanent damage. 

Ashland admitted that Uie usual testing procedures were not employed before putting tlie tank into service. Hydrostatic testing is recommended by the American Petroleum Institute, but pumps large enough to gel water to the lop of tlie lank were not tnailable at the site. An alternate procedure was performed in which the lank was sprayed with diesel fuel and subjected to a vacuum. However, the lank was not inspected by any outside agency prior to use. 

Following the completion of a new boiler installation, it must be inspected and any remaining debris must be removed, It is then subjected to hydrostatic testing and chemical cleaning prior to startup. 

These same diamine materials find further application in, for example, formulations for mussel and barnacle control in large once-through, condenser cooling systems, as corrosion inhibitors and biostats for hydrostatic testing of oil and gas pipelines, and as corrosion inhibitors in food industry retort cookers. 

Next, the boiler must be passivated. The boiler is filled above normal working level and ammonia/hydrazine or a similar passivation treatment is added. The boiler is first given a hydrostatic test. Following this, the water level is dropped, and the boiler is lightly fired for 4 to 6 hours to ensure adequate passivation of the boiler surfaces. 

The application of a clamp on a SV spindle to keep the valve in a fully-closed position, especially during a hydrostatic test. 

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