Fabricated piping hazardous materials

The manufacturer usually sees to the testing of shop-fabricated vessels and pipework in accordance with vessel and piping design specifications. The owner s inspectors often witness these tests, which may be those required for Code certification. Further testing on site will verify that joints are leak-tight, and it is particularly valuable on systems that handle hazardous materials. Testing of site-fabricated pipework is done in place in accordance with the piping specification. 

Figure 12.17 Fabricated piping should be tested prior to conveying hazardous materials. Usually piping is hydrotested. This is a rare failure of a 24-in. piping elbow.

Lead and Lead-Lined Steel Pipe Lead and lead-hned steel lipe have been essentially eliminated as piping materials owing to lealth hazards in fabrication and installation and to environmental objections. Lead has been replaced by suitable plastic, reinforced plastic, plastic-lined steel, or high-alloy materials. 

In a given situation, it may prove more economic to install a cheaper material with a high corrosion rate and replace it frequently rather than select a more resistant but more expensive material. This strategy would only be considered for relatively simple equipment with low fabrication costs, and where premature failure would not cause a serious hazard. For example, carbon steel could be specified for an aqueous effluent line in place of stainless steel, accepting the probable need for replacement. The pipe wall thickness would be monitored in situ frequently to determine when replacement was needed. 

Codes establish the minimum requirements for design, fabrication, materials, installation, inspection, and testing for most piping systems. Thermoplastics used for plumbing, sewer, water, gas distribution, and hazardous waste may come under the jurisdiction of a code or regulation. Some of the most frequently used codes for plastic piping products used for water and gas applications are ... 

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