How to Test and Inspect PVC Hose Pipe？
Testing and inspection in PVC hose pipe manufacturing may be divided into three categories:
(1) Qualification testing
(2) Quality control testing
(3) Assurance testing
Qualification testing is performed on piping products and on the materials from which they are produced to ensure that the finished products meet the requirements of applicable specifications. Qualification testing must demonstrate that the materials, process equipment, and manufacturing technology consistently yield, through proper production procedures and controls, finished products that comply with applicable standards.
This qualification test is performed to verify that metals and chemicals cannot be extracted by water in quantities termed toxic, carcinogenic, teratogenic, or mutagenic, which produce adverse physiological effects in humans. The test, as specified in ANSI/NSF 61, is required for all PVC potable-water piping materials and products.
Long-term hydrostatic strength testing.
This qualification test is required and performed to establish the maximum allowable design (tensile) stress in the wall of PVC pipe in a circumferential orientation (hoop stress) as a result of internal pressure applied continuously with a high level of certainty that failure of the pipe cannot occur.
Joint performance testing.
This qualification test is performed to verify a leak-free design of a specified pipe joint that will maintain a proper connection and seal.
This test is used to verify that fabricated-fitting solvent-cementing procedures result in minimum average lap-strengths of 900 psi (6.2 MPa). Lap-sheer test samples are produced by solvent-cementing of component pipe segments identical to those that are used to fabricate fittings.
Quality Control Testing
Quality control testing is routinely performed on specimens of PVC piping products as they are manufactured to ensure that the products comply with applicable standards. Quality control testing includes, but is not limited to, inspection and testing to verify proper dimensional, physical, and mechanical properties. Frequently, quality control tests are required that may not define a desired finished product property but that do verify the use of proper procedures and controls in the manufacturing process. Quality control tests and inspection required in the manufacture of C900, C905 PVC, and C909 PVCO products are as follows.
Inspection is conducted to ensure that the PVC pipe product is homogeneous throughout—free from voids, cracks, inclusions, and other defects—and reasonably uniform in color, density, and other physical properties. Surfaces are inspected to ensure that they are free from nicks, gouges, severe scratches, and other such blemishes. Joining surfaces shall be ensured freedom from damage and imperfections.
Inspection verifies proper marking of the pipe as required in the applicable product standard. Marking of C900, C905 PVC, and C909 PVCO pipe includes the following:
• PVC or PVCO
• Manufacturer’s name or trademark and production-record code
• Nominal pipe size
• Outside diameter regimen (C905 only)
• Dimension ratio (for example, DR 25)
• Pressure class or pressure rating (for example, PC 100)
• Standard designation (for example, C900)
• Seal of the testing agency that verified the suitability of the pipe material for potable-water service (optional)
Measurement of dimensions on a regular and systematic basis is essential. Failure to meet dimensional requirements may render the product unsatisfactory regardless of success in other inspections and tests. All dimensional measurements are made in accordance with ASTM D2122 and include the following:
• Product diameter
• Product wall thickness
• Bell joint dimensions
• Fabricated-fitting configurations
Some dimensional requirements are defined in the manufacturer’s product specifications. Markings of machined couplings and fabricated fitting includes the following:
• Nominal size and deflection angle (if applicable) • PVC
• Pressure class or pressure rating
• Standard designation
• Manufacturer’s name or trademark
• Seal of the testing agency that verified the suitability of the PVC material for potable-water service (optional)
Product packaging inspection.
The finished package of PVC pipe prepared for shipment to the customer is inspected to ensure correct pipe quantity and adequate protection of the pipe.
The PVC pipe sample is pressurized to burst within the test time period of 60–70 sec. Burst pressure measured must not be less than minimum burst pressure requirements defined in C900 or C909. Quick-burst testing is conducted in accordance with ASTM D1599. This test is also performed on machined couplings.
The PVC pipe specimen is partially flattened between moving parallel plates. When the pipe is flattened 60 percent (the distance between the parallel plates equals 40 percent of the original outside diameter), the specimen should display no evidence of splitting, cracking, or breaking.
Extrusion quality test.
The PVC pipe specimen is immersed in anhydrous (dry) acetone for 20 min. When removed from the acetone bath, the pipe specimen should pass the failure criteria in ASTM D2152. Extrusion quality testing is conducted in accordance with ASTM D2152 and distinguishes only between unfused and properly fused PVC pipes.
Quality control inspection and testing must not be confused with field acceptance testing. Quality control testing is only appropriate during or immediately following the manufacturing process.
Arc test for fabricated fittings.
The arc test is required for butt-fused or thermally welded joints in fabricated fittings. Any discontinuity in a segment joint is indicated by the presence of an arc (spark) from a probe tip and is cause for rejection of the fitting.
Fabricated-fitting pressure test.
In this test, the fabricated fitting must not fail, balloon, burst, or weep when subjected to an internal pressure test. For C900 fabricated fittings, the internal pressure test is equal to four times its designated pressure class for a minimum of one hour. For C905 fabricated fittings, the internal pressure test is equal to two times its designated pressure rating for a minimum of two hours.
Assurance testing is performed at the completion of the manufacturing process to assure the finished products consistently and reliably satisfy the requirements of applicable standards. Quality assurance tests required in the manufacture of C900, C905 PVC, and C909 PVCO products are as follows.
Sustained pressure test.
C900 pipe or fabricated fittings shall not fail, balloon, burst, or weep, as defined in ASTM D1598 at the applicable sustained pressure when tested for 1,000 hr as specified in ASTM D2241.
Hydrostatic proof test.
The hydrostatic proof test is required in the manufacture of PVC pipe and machined couplings in accordance with C900, C905, and C909. In the test, every coupling and piece of PVC or PVCO pipe is proof-tested
for a minimum dwell time of 5 sec. C900 and C909 require the hydrostatic proof test to be conducted at four times the pressure class (i.e., 4 × 150 psi = 600 psi for DR 18 pipe). C905 requires that the hydrostatic proof test be conducted at two times the pressure rating of the pipe (i.e., 2 × 235 psi = 470 psi for DR 18 pipe).