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August 23, 2016
Repair Design: Are you following the right standards?

Posted by: Casey Whalen

As we mentioned in a previous blog post, it is imperative that the design of the repair is in accordance to current standards and that proper due diligence is performed to ensure all scenarios are accounted for, regardless of the system used.

All composite repairs should follow either the ASME PCC-2 or ISO 24817 Standard. Both of these standards are used to determine a minimal repair thickness using pipe properties as well as composite properties. This minimal repair thickness is then translated to a layer count based on the fabric’s thickness.

Using the hoop values stated previously, and a generic pipe (X35; 12” NPS; 0.375” thickness; 80 percent wall loss; 1,000 psi) a comparison can be made using equation 6 in the ASME PCC-2-2011 Article 4.1 (pg. 144) which is reprinted below:

Repair_Design_Formula.png

Where εc is dictated as 0.25% by the standards (under these example conditions), Ec is listed previously as Hoop Modulus, P = 1,000 psi; D = 12.75”; s = 35,000 psi; ts = 0.75”.

Repair_Design_Chart.png

Looking at this design example, Atlas is the thinnest repair. For this non-leaking example design, we would typically recommend the more economical A+ Wrap.

Different defects and scenarios will largely dictate which repair system is best. For example, a dent requires a repair with a high modulus to prevent the dent from straining. For that reason, Atlas is typically recommended, regardless of cost.

It’s better to have a good repair than a cheap repair.

Ready for a deeper breakdown of ASME and ISO standards for your next pipe repair project? Contact Casey and our team of dedicated technical reps.

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Category: Pipe Wrap

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