How times have changed in 30 years regarding “materials of construction” in hazardous materials processes. I grew up in process safety, seeing nothing but metallic piping systems; today, I bet I see piping systems made from non-metallic products upwards of 25% of the time. This is becoming increasingly acceptable in one specific process I do a lot of work with, so I can not provide specifics as it could create a trail back to some of my clients. Just know that many of the processes are PSM/RMP-covered processes.
ASME B31.3 addresses non-metallic piping systems in Chapter VII, Nonmetallic Piping and Piping Lined With Nonmetals.
In this article, I want to discuss Part 10, Inspection, Examination, and Testing of Nonmetallic Piping Systems Used in a PSM/RMP-covered process. For those who are not SAFTENG members, just know that ASME B31.3 requires many of the same examination and testing requirements for nonmetallic piping systems as it does for metallic piping systems. Two (2) very CRTICIAL PROHIBITIONS for non-metallic piping are the SAME as metallic piping:
- PVC and CPVC piping shall NOT be pneumatically tested!
-
Initial Service Leak Test applies in its entirety for Category D Fluid Service ONLY!
Here are the other examination and testing requirements for NON-metallic piping systems:
Paragraph 340 -INSPECTION applies in its entirety.
Paragraph 341.1 GENERAL applies.
Paragraph 341.2 RESPONSIBILITY FOR EXAMINATION applies in its entirety.
- Responsibility for Examination applies, except for (a) and (b), which apply only to metals.
- Acceptance criteria shall be as stated in the engineering design and shall at least meet the applicable bond requirements in Table A341.3.2
- Defective Components and Workmanship apply in their entirety.
- Progressive Sampling for Examination applies in its entirety.
EXAMINATION PERSONNEL
Paragraph 342 applies in its entirety.
EXAMINATION PROCEDURES
Paragraph 343 applies in its entirety.
TYPES OF EXAMINATION
Paragraph 344.1 applies in its entirety.
- Visual Examination – Paragraph 344.2 applies in its entirety.
- Radiographic examination may be used in accordance with para. 344.1.2.
- Ultrasonic examination may be used in accordance with para. 344.1.2.
- In-Process Examination applies in its entirety.
TESTING
Required Leak Test
(a) Prior to initial operation, each piping system shall be tested to ensure tightness. The test shall be a hydrostatic leak test in accordance with para. A345.4, except as provided herein.
(b) Paragraphs 345.1(a) and (b) apply.
Preparation for Leak Test
Paragraph 345.3 applies in its entirety, considering bonds in place of welds, and excluding expansion joints.
Hydrostatic Leak Test
Test Fluid – Paragraph 345.4.1 applies.
Test Pressure
(a) Except as provided in para. A345.4.3, the hydrostatic test pressure at any point in a nonmetallic piping system shall be not less than 1.5 times the design pressure, but shall not exceed 1.5 times the maximum rated pressure of the lowest rated component in the system.
(b) For piping systems in which the design temperature is above the test temperature, para. 345.4.2(b) applies, except that S and ST shall be from Table B-1 instead of A-1.
(c) Metallic Piping with Nonmetallic Lining – Paragraph 345.4.2 applies.
Pneumatic Leak Test
In addition to the requirements of para. 345.5.1 a pneumatic test of nonmetallic piping is permitted ONLY with the owner’s approval
- precautions are in Appendix F, para. FA323.4 should be considered
Other Requirements
(a) Paragraphs 345.5.2 through 345.5.5 apply
(b) PVC and CPVC piping shall NOT be pneumatically tested
Initial Service Leak Test
Paragraph 345.7 applies in its entirety for Category D Fluid Service ONLY.
RECORDS
Paragraph 346 applies in its entirety.