The OPS has issued a proposed response to the following Frequently Asked Question relating to temporary pressure reductions after identification of an immediate repair condition:
Question: FAQ E.1: Section 195.452(h)(4)(i) requires that I temporarily reduce pressure in response to an immediate repair condition. The same paragraph also requires that I must calculate the reduction using the formula in section 451.7 of ASME/ANSI B31.4. If using that formula results in a calculated safe pressure that is higher than my original operating pressure, must I still reduce pressure? To what?
The Proposed Answer is as follows:
Proposed Answer:Yes. A pressure reduction is required to provide additional safety margin until an immediate repair condition can be addressed. OPS expects that situations in which the calculated safe pressure using the formula in section 451.7 of ASME/ANSI B31.4 is higher than the original operating pressure will be rare. Nevertheless, if the calculated pressure is greater than the existing operating pressure, pressure must still be reduced to provide the necessary margin. Operators should determine the amount of such reduction based on their particular circumstances.
Operators should also note that the specified formula only applies to metal loss anomalies (i.e., corrosion). It does not apply to immediate repair conditions that do not involve metal loss, nor does it apply to dents with metal loss. For those circumstances, operators must determine an acceptable method for calculating an acceptable reduced operating pressure. A reduction of 20 percent below the highest operating pressure actually experienced at the location of the defect within the two months preceding the inspection may provide the necessary additional safety margin. (See FAQ 7.15)
Opportunity for comment is available by going to the following website: primis.phmsa.dot.gov/iim/faqeval.htm