Test method hydrostatic

Water resistance test methods include AATCC 127 (hydrostatic pressure test), AATCC 42 (impact penetration test), and AATCC 35 (rain test). In the hydrostatic pressure test, a sample is subjected to a column of increasing water pressure until leakage occurs. The impact penetration test requires water to be sprayed on the taut surface of a fabric sample from a height of two feet. The fabric is backed by a blotter of predeterrnined weight, which is reweighed after water penetration. The rain test is similar in principle to the impact penetration test. 

The rain test simulates the effects of rainfaU the hydrostatic head on the spray controls the intensity of spraying. The repeUency is rated by the weight of water that penetrates the fabric and is absorbed by a blotter mounted behind the fabric at a specific intensity of spraying (AATCC Test Methods 35 and 42 INDA Standard Test 80.2-92). 

The hydrostatic-pressure test is performed on fabric mounted under the orifice of a conical weU. The fabric is subjected to increasing water pressure at a constant rate until leakage occurs at three poiats on the fabric s undersurface. The rating is the height of the water head ia centimeters above the fabric (AATCC Test Method 127 INDA Standard Test 80.4-92). 

Piping required to have a sensitive leak test shall be tested by the gas- and bubble-formation testing method specified in Art. 10, Sec. V of the ASME Code or by another method demonstrated to have equal or greater sensitivity. The sensitivity of the test shall be at least (100 Pa mL)/s [(10 atm mL)/s] under test conditions. If a hydrostatic pressure test is used, it shall be carried out after the sensitive leak test. 

The laminate compressive hoop strength/stiflness of a filament-wound vessel can be evaluated using the externally pressurized ring test method [44] or the standardized ASTM D2586 test method. In the ASTM D2586 test method a filament-wound FRP cylinder is tested under hydrostatic pressure to simulate the loading conditions of a pressure vessel under an external pressure load. The main drawback of this test method is the influence of the end constraints on the test results. 

Test methods will logically include tensile testing to measure strength, and hydrostatic testing at a pressure with a liquid to test for leaks. Pressures not exceeding 300 mm Hg pressure (internal heart fluid pressure) could be employed for this purpose. 

AATCC Test Method 35 -2000 " is designed to simulate a rain event. A special apparatus is used to hold the 20 x 20 cm fabric sample in a vertical position backed by a weighed piece of blotter paper. The fabric face is sprayed with water under constant hydrostatic pressure for 5 min and the blotter paper reweighed. The increase in weight of the backing paper is a measure of the resistance of the fabric to penetration by the simulated rain. 

Preliminary testing is done next to uncover flaws in joining, and sometimes in the metal itself. Nondestructive test methods, such as ultrasonics and X- or gamma-ray inspection, are used on main welding seams Dye penetration, hydrostatic, or air-soap tests are also used to locals leaks and cracks. Helium or Freon leak detectors are necessary fok more critical leak testing, particularly on high-vacuum equipment. 

The AATCC-127 and ISO 811 test methods measure the resistance of a fabric to the penetration of water under hydrostatic pressure. A test specimen mounted under the orifice of a conical well is subjected to water pressure constantly, increasing at 10 0.5 cm per minute until three leakage points appear on its surface, as shown in Fig. 2.13. The higher the column height achieved before the appearance of the third water droplet on the fabric surface, the greater is the water resistance of the specimen. 

Many fabrics can withstand a hydrostatic head of 130cm but the vapour transmission rates are often difficult to compare because of the variety of the test methods and also because the conditions during the tests do not even remotely reflect the extreme external conditions (e.g. rainy weather) for which the fabrics are designed. 

AATCC test method 127-2003. Water resistance hydrostatic pressure test. AATCC technical manual, vol. 82. 2007. 

EN 804 Injection-moulded socket fittings for solvent cemented joints for pressure piping -test method for resistance to a short-term internal hydrostatic pressure. 

EN 911 Elastomeric sealing ring type joints and mechanical joints for thermoplastics pressure piping - test method for leaktightness under external hydrostatic pressure. 

ASTMD2837 2001a Standard Test Method for Obtaining Hydrostatic Design Basis for Thermoplastic Pipe Materials... 

ASTM D 5514 1994 Test Method for Large Scale Hydrostatic Pnnctnre Testing of Geosynthetics... 

Specification 3A, 3AA, and 3B cylinders used in methylamine service must be requalified by hydrostatic retest every 5 years under present regulations. Specification 4B, 4BA, and 4BW must be hydrostatically tested after expiration of the first 12-year period and each 7 or 12 years thereafter depending on the initial hydrostatic test method. Cylinders in compliance with specifications 3A, 3AA, 3B, 4B, 4BA, or 4BW that are used specifically for monomethylamine, dimethylamine, and trimethylamine service and are free from corroding components may also be qualified by an external visual inspection as described in CGA C-6, Standards for Visual Inspection of Steel Compressed Gas Cylinders [10]. Periodic hydrostatic retest is not required for specification 3E cylinders. 

Contrary to the strip test to measure the amount of hquid wicking into an in-plane of nonwoven fabric, the demand absorbency test (also referred to as the demand wettability test or the transverse wicking plate test) measures the hquid wicking into the nonwoven fabric driven by the capUlary pressure in the direction of fabric thinness.In demand absorbency tests, the hquid wUI only enter into the fabric when the sample demands it. These tests involve contacting the dry sample with a hquid in such a way that absorption occurs under a zero or shghtly negative hydrostatic head. No standards for this test method are currently available. 

The waterproofness test method for surgical dressings is described in the BP. The waterproofness test apparatus consists of the application of a hydrostatic head of 500 mm of water to a circular area about 20 cm of the nonadhesive side of the dressing. A filter paper (55 mm in diameter) is applied to the adhesive side. The dressing is deemed to comply with the waterproofness test if no water passes through it in at least five of a total of six specimens tested. 

Regardless of the type of hydrostatic testing method used, DOT and TC regulations both specify that the periodic retest must include an external and internal visual examination of the cylinder. It is recommended that these inspections be conducted prior to the hydrostatic retest in accordance with the applicable Compressed Gas Association standards. See references [13] through [16] and [20]. External and internal inspection considerations were discussed more thoroughly in previous sections of this chapter. 

Acoustic emission testing using hydrostatic and/or pneumatic pressure is presently allowed by DOT exemption only and therefore will be addressed only by definition in this chapter as follows Acoustic emission is defined as the transient elastic waves generated by the rapid release of energy within a material. Acoustic emission technology is simply a method that listens to abnormal sounds... 

Resistance to crack propagation for slow crack growth on notched pipes of wall thickness greater than 5 mm test method EN ISO 13479. It is expressed in terms of time to failure in a hydrostatic pressure test on a pipe with machined longitudinal notches in the outside surface. 

Elevated temperature service (hydrostatic design basis determined at the specified higher temperature) test method ASTM D 2837. 

Determination of the long-term hydrostatic strength of fittings, valves, and ancillary equipment test method EN 12107. 

Test Methods for Determining Long-Term Hydrostatic Strength... 

Table 11 shows the results of open porosity for the samples before and after aluminum electrolysis, which are tested by hydrostatic method. Obviously, all the sample porosity after aluminum electrolysis had been decreased, which was due to flie pores within the cathode samples filled with the molten electrolyte during aluminum electrolysis. Furfliermore, the carbon cathode sample without the function and gradient layers had file biggest increase in open porosity after electrolysis (about 18.26%), while TG2 sample with FGM layer was file lowest (about 6.34%). This means that the FGM cathode had the least penetrated electrolyte filled into the inner pores, which are in good agreement with SEM observation illustrated above. 

The two types of pressure testing are hydrostatic and pneumatic. Hydrostatic pressure testing with clean water is the preferred method. The test section should be completely filled with the test medium, taking care to bleed off any trapped air. Venting at high points may be required to purge air pockets while the test section is filling. 

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