Behind Closed Doors: Pipeline Closures Revisited
Proceedings Publication Date
Alan Morton
Alan Morton, Kolton Landreth
Part of the proceedings of

Pipeline doors or “closures” are commonplace in the pipeline industry, providing access to the pipeline itself as well as to high-pressure equipment associated with the pipeline such as filters, separators, strainers, etc. Despite their prevalence, the importance of closures to the safe and efficient operation of a pipeline system is often overlooked. Recent changes in closure definitions and terminology warrant a review of the systems, applicable standards, designs and considerations related to choosing a closure for a desired purpose.


The industry defines what a closure is in a variety of ways. One definition, for example, is a pressure-containing component used to blank off an opening nozzle on a vessel or end of pipeline — which could mean a bolted blind flange, a T-bolt cap or a “quick-opening” closure.  ASME B31.4 and ASME B31.8 defines a “quick-opening” closure as a pressure-containing component used for repeated access to the interior of a piping system. ASME VIII-1 UG-35.2 (a) (1) defines quick-actuating closures while UG-35.3 (a) (1) defines “quick-opening” closures, both of which permit substantially faster access to the contents space of a pressure vessel than would be expected with a standard bolted flange connection. There are several ways the current codes can be interpreted, but what does it all mean?

 This paper will present a history of pipeline closures from the early development to recent innovations. The paper will address:


  • The different type of closures available and pros and cons of each.
  • Safety systems
  • The importance of the sealing element, including material, where it is located, how it is energized, low pressures, rapid decompression issues, etc.
  • Locking elements versus Holding elements.
  • The importance of proper maintenance.
  • The use of the appropriate materials.
  • Horizontal versus vertical configuration.
  • Offshore versus onshore operation.


Keywords: Pipeline, Closures, Quick-Opening, Quick-Actuating, ASME B31.4, ASME B31.8, ASME Section VIII.

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