Interpretation Response #PI-15-0011 ([National Oilwell Varco L.P.] [Mr. John K. Arnold])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: National Oilwell Varco L.P.
Individual Name: Mr. John K. Arnold
Location State: TX Country: US
View the Interpretation Document
Response text:
Mr. John K. Arnold, Esq.
WINSTEAD
1100 JP Morgan Chase Tower
600 Travis Street
Houston, TX 77002
Dear Mr. Arnold:
In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated October 20, 2015, you requested an interpretation of 49 CFR Part 195. You asked if the requirements of Part 195 exclude the use of mechanical interference connections.
You stated that NOV Tuboscope, a division of National Oilwell Varco LP, is proprietor of a pipeline mechanical connection technology known as Zap-Lok. You stated that Part 192 appears to allow a mechanical connection to steel pipes according to a 1972 interpretation, but there is no similar interpretation for Part 195 that either allows or prohibits the use of such connection method.
You stated that in 2014, a Texas pipeline operator utilized the Zap-Lok mechanical connection to join sections of pipe in a 12-mile condensate pipeline within an area subject to the pipeline safety jurisdiction of the Railroad Commission of Texas (RCT). After the operator completed construction of the 12-mile pipeline, a RCT inspector notified the operator that mechanical interference connections were prohibited for liquids lines under Part 195 of the federal pipeline safety regulations and the Texas pipeline safety regulations. You stated, however, that RCT has never concluded that this is the case in any formal action. You stated that, in order to timely complete and activate the condensate pipeline, the operator was forced to dig up the entire pipeline, cut out the mechanical connections, and weld the joints before putting the pipeline back into place. You stated that, based on the 2014 RCT action, certain operators of liquid pipelines in Texas have expressed a concern to NOV Tuboscope that RCT’s actions in this matter constitute an official PHMSA interpretation as to the use or prohibition of mechanical pipeline connections under Part 195.
You pointed out § 195.424(c) is an indicator that a non-welded joint may be permitted under Part 195. In addition, you stated that § 195.8 allows an operator to use a pipeline material other than steel if PHMSA determines its use would not be unduly hazardous and, therefore, the section supports the notion that a mechanical joint is not prohibited where it meets the required pipeline performance standards. Therefore, you request an interpretation whether the federal pipeline safety regulations allow mechanical connection of steel pipelines under Part 195.
You are correct that Subpart F of Part 192 allows joining of materials other than by welding, but not for steel pipe to pipe joining. Also, PHMSA agrees with you that it is the pipeline operator’s responsibility to demonstrate that the pipeline material is suitable and the joining procedures are acceptable for the intended service. Subpart E of Part 192 and Subpart D of Part 195 have specific requirements for welding of steel pipe to steel pipe. However, there are no such federal pipeline safety requirements for the Zap-Loc steel pipe to steel pipe connection method.
In addition, the regulations embody the principle long established in the boiler and pressure vessel standards that says any pipe fitting or component must be at least as strong as the pipe itself and able to withstand anticipated loading and stresses without impairment of its serviceability (Part 192, Subpart C and Part 195, Subpart C). Joining steel pipe and fittings by proper welding procedure accomplishes this. Also, joining steel pipe by certain types of mechanical means, such as the use of a flange fitting, also accomplishes this. However, if joining by press-fit would not be as strong as the pipe wall itself, the principle of having a pipe fitting that is at least as strong as the pipe itself would be violated.
The strength requirement includes not only hoop strength, but also strength against longitudinal pullout, or thrust forces causing an axial separation that would result in sudden complete failure or in seepage of gas or hazardous liquid from the connection over time. An operator would need comprehensive test data including data for all of the forces that can be expected to act on the pipe over its entire service lifetime. Such forces include expansion and contraction, cyclic internal loading forces, surge pressures, pressure cycle fatigue, bending forces, dents, corrosion, and maintaining longitudinal strength for the given service in which the pipe would actually be used.
A few specific examples of code requirements that the operator would be faced with include: §§ 192.55 and 195.112(b) and API 5L do not allow for pipe ends to be expanded for up to 10 percent of diameter; §§ 192.105 and 195.106 and API 5L involve limitations on maximum increases (and decreases) in pipe diameter; §§ 192.109 and 195.106 and API 5L involve limitations on maximum increases (and decreases) in wall thickness and uniformity of transition connection thickness; and pipe must be suitable for its intended purpose and pipe ends would need to be analyzed for mechanical and chemical properties, cold expansion effects, cracking, laminations, hardness, diameter change transition effects, and longitudinal friction effects.
Also, with this pipe fitting method, compliance with numerous other code sections including, among other things, corrosion control programs, integrity management impacts, dent remediation, passage of in-line inspection tools, etc., would likely be in question.
Therefore, in the absence of such requirements and/or quality control methods, the Zap-Loc pipe-to-pipe fitting method does not meet the federal pipeline safety regulations.
If we can be of further assistance, please contact Tewabe Asebe at 202-366-5523.
Sincerely,