Surveillance of Construction Activities Surveillance is another area that requires good communication to be successful. The owner needs to set the criteria on surveillance, such as type of inspections and frequency. This is where the owner and inspector need to establish the extent of examination. This extent can then be communicated to the contractor. A key point to consider is that inside diameter inspection opportunities are limited. Develop a surveillance plan to maximize visual inspection of these areas. Final Visual Exam This needs to happen in two stages, before and after postweld finishing or conditioning. This gets to be an issue when an inspector is called to look at a weld and finishing has already been performed. This makes it impossible to properly visually examine the weld. At this point, visual verification of bead width, meandering, convexity, concavity, etc., are no longer available. These are issues that may require a cutout and replacement of the entire weld. The AWS D18.1/D18.1M Sec. 6 has easy-to-understand inspection criteria accompanied with illustrations — Fig. 2. The other area of concern for the inspector is color or discoloration of the inside diameter. Contained in AWS D18.1/D18.1M, Fig. 3 shows different levels of discoloration. This illustrated example needs to be reviewed by all parties to determine the desired maximum discoloration that will be allowed on the project. The inspector should not be determining the quality in this case; however, advising the owner that more oxidation typically leads to reduced corrosion-resistant properties is appropriate. But again, the inspector should not determine quality levels. Systems as these can carry varied levels of corrosive media that need to be addressed by the owner’s responsible engineer. Just from personal experience, I typically see discoloration quality of 3 and less acceptable and easily attainable with simple industrial grade argon purge and shielding gas. Some contributing factors that lead to discoloration are moisture in the gas or on the materials to be joined; particulates from cleaning, and off gassing of cleaning solvent residue on surfaces to be joined; grade of material’s surface finish; poor purge sealing; and leaks in hoses and loose connections. Keep This Standard Handy This information presented is an overview of some areas to watch for, and good practice recommendations. I recommend any inspector engaging in this scope should possess and understand the contents of AWS D18.1/D18.1M. Just think.What you inspect might be the very same equipment that puts food on your family’s dinner table. specialists in 3D profiling 20 Inspection Trends / April 2013 Fig. 3 — Levels of discoloration. MICHAEL LANG is chairman of the AWS D10 Committee on Piping and Tubing and a member of the AWS D18 Committee on Welding in Sanitary Applications. “It Used To Take Us 8–10 Hours To Prepare A Typical Pressure Vessel Shell. It Now Takes About An Hour.” Kurt Schaerer Enerflex General Manager HGG Profiling Machinery has dramatically improved productivity & reduced rework, while helping the company move towards a fully integrated automated system. In addition, Enerflex plant capacity has increased 25 to 30%. For the full Enerflex Case History, ask for our new Profiles In Automation, or for the link to our YouTube Enerflex Case History. Follow Us: HGG Americas www. hgg-group.com Email: americas@hgg-group.com Tel: 1-330-461-6685 For info go to www.aws.org/ad-index
Inspection Trends | April 2013
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