Quick Opening Closure (QOC)

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What is it and what is its purpose?

Quick Opening Closure (QOC) consists of a hub, a cover and a locking system complete with suitable sealing gasket.

Typical applications of the QOC are:
installation on the access opening of a pressure vessel
installation on scraper traps

QOC opening / closing time is much lower if compared to a standard blind flange (for example according to ANSI B16.5 or ANSI B 16.47) with bolts/nuts, so maintenance time is quicker and easier.

Design and Construction

QOC are designed, engineered and manufactured according to the most stringent international standards applicable to Pressure Vessels for Oil, Gas and Petrochemical industry such as ASME VIII div. 1 & 2, ISO EN 13445.

Moreover new design is always verified by the Finite Element Analysis (FEA).

QOC can be certified according to PED and ATEX, therefore it can be equipped with a proper CE marking.
QOC can be U-Stamp certified (partial U-stamp) for the installation on U-Stamped pressure vessel.
QOC is always foreseen with safety warning device as per requirement of ASME code (UG-35).
QOC can be manufactured in carbon steel, stainless steel, carbon steel with cladding overlay on the sealing surface of gaskets.

Accessory Instrumentation

QOC is always supplied complete either with davit (for vertical installation) or with hinge (for horizontal installation) and with safety warning device as per code.

The following additional accessories can be supplied on request:
– key interlock system
– limit switches for open/close position feedback
– single point for opening/closing operation
– protection cover to protect the closure from dust and dirty

Market presence

Forain has supplied pressure vessels equipped with QOC Worldwide.


Forain started the supply of filters and separators equipped with QOC in 1975.
The first type was the standard QOC according to ASME VIII Div.1 App.24 (jaws type).

As years went by, Forain developed some alternative types (jaws V-type, sector type, threaded type).
Forain can also supply any type of closure, according to customer’s request and applicable vendor list.

Contact us for more information