Interpretation Response #PI-14-0017
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Mr. Jody R. Arner
Air Products and Chemicals, Inc.
7201 Hamilton Boulevard
Allentown, PA 18195-1501
Dear Mr. Arner:
In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated September 18, 2014, you requested an interpretation on the manner in which structures are counted for purposes of determining class location along a gas pipeline. Specifically, your questions involved the use of "clustering" of buildings as referenced in 49 CFR 192.5(c)(2). In particular, you asked whether there is any overall length limit to the application of clustering.
You provided an example diagram (attached) and explained the diagram as a hypothetical cluster of buildings extending for 1.15 miles in a Class 3 location. You stated that because the length exceeds 1 mile, you would like to know if clustering is allowed under § 192.5(c) to end the Class 3 location at 220 yards from the end of the 1.15 miles. You stated that there are few structures on either end of the cluster in the example you provided, but not within 220 yards at the end of the 1.15 miles. You stated that if any structure(s) would be present outside of the 220 yards that would result in a Class 3 sliding mile count, then that structure(s) would be given Class 3 status over the appropriate length as required.
Under § 192.5(a), the class location unit establishes the class location, identifying the highest concentrations of dwellings along the pipeline in a continuous mile of pipeline. As you slide the class location unit down the pipeline for 220 yards, as soon as you encounter a higher concentration of dwellings, you have a higher class location (see Graphic 1). Section 192.5(c) allows an operator to cluster or reduce the amount of pipe that is subject to the requirements of a higher class location.
A Class 3 location can be longer than a mile or shorter than a mile when using the clustering method. As illustrated in Graphic 2, if a class location unit is determined to be Class 3 with a group of homes on one end (A) and a group of homes on the other end (B), the amount of pipeline that would be subject to Class 3 requirements can be reduced by the application of clustering. To cluster, the operator could establish the Class 3 location limit 220 yards on the upstream side of (A) and 220 yards on the downstream side of (A). The same would be repeated for (B) at the other end of the class location unit. The pipeline between these two clusters is still in a Class 3 location; it is just not subject to the requirements of a pipeline in a Class 3 location. If the 220 yard limits intercept or overlap between the two clusters, then clustering between the two groups would not be applicable and the entire length of the pipeline from 220 yards upstream of (A) to 220 yards downstream of (B) would be subject to the Class 3 location requirements.
We hope this clarifies the application of clustering in § 192.5(c). If we can be of further assistance, please contact Tewabe Asebe of my staff at 202-366-5523.
John A. Gale
Director, Office of Standards
T:PHP-30:Interps:Open:Air Products-PI-14-0017-10-01-2014-Part 192.5
|§ 192.5||Class locations|