Quick actuating closures are in widespread use throughout industry. Quick-actuating or quick-opening closures are those that permit substantially faster access to the contents space of a pressure vessel than would be expected with a standard bolted flange connection. The design to insure that his autoclave door offers adequate protection against the maximum pressures carried by these closures and to further insure that interlocking devices are provided which will prevent the door from being opened while the vessel is still pressurised.
Quick Actuating Closures can be classified as:
- Interlocking lug type;
- Expanding or contracting ring type;
- Clamp type;
- Cam latch/bayonet catch type;
- Bar locking type;
- Swing bolt type
- Yoke type
- Threaded type
The cam latch type and clamp ring type are preferred, particularly in the larger sizes, for ease of operation.
Design features of the various locking mechanisms
Various designs of safety devices have been developed to prevent this from happening.
One safety device is a pressure actuated unit that prevents the admission of pressure into the vessel until the door is fully closed and locked, and prevents opening of the door until the pressure within the vessel has been reduced to atmospheric.
Another simple safety device is a pin design which prevents closing of the vent valve until the door is in the completely closed position. The hole in the flange lines up with the pin, permitting its inward movement and the rotation of the valve stem to its closed position. Conversely, disengagement of the end closure is prevented by the pin unless the valve has been turned to the wide open position, thereby venting the vessel.
Still another simple safety device that can be made in the plant if desired consists of a vent valve of the rising stem type with an arm attached to the stem of the valve. A pin on the end of the arm prevents closing of the vent valve unless the door is properly closed and locked so that the pin can enter holes in the door ring and door which are aligned only when the door is in the fully closed and locked position. Conversely, the door cannot be opened unless the vent valve is fully open.
There are a number of other types of mechanical interlocks available as well as electrical, hydraulic and pneumatic safety devices. Safety interlocks are occasionally interconnected into process control systems. In some instances the vessel should remain closed until flammable, toxic, or other hazardous material in gaseous or liquid forms have been removed and the vessel purged. These materials may be in the vessel under essentially atmospheric pressure conditions.
Safety implications for these safety locking devices are covered by the essential safety requirement Annex I Section 2.3 of the PED. This control equipment could be of a simple self-acting type or of a more complicated type, e.g. with a pressure transmitter and an actuator. This safety devices are not safety accessory according to the Pressure Equipment Directive (PED).
Design Codes for Quick-Actuating Closures (QAC) and Quick-Opening Closures (QOC)
Quick-opening closures installed on pressure vessels are normally designed to the Codes and Rules for pressure vessels and piping:
| EN 13445 | ASME BPVC Sect. VIII Div. 1 | ASME BPVC Sect. VIII Div. 2 | ASME B31.3, ASME B31.4, & ASME B31.8 | |
|---|---|---|---|---|
| Design requirements | EN 13445 | UG-35.2/35.3 App. 24 | Part 4 and 5; Par. 4.8 | ASME BPVC Sect. VIII Div. 1 UG-35.2/35.3 App. 24 |
| Safety devices requirements | PED: Annex I Section 2.3 | ASME BPVC Sect. VIII Div. 1 UG-35.2/35.3 | Par. 4.8 | ASME BPVC Sect. VIII Div. 1 UG-35.2/35.3 |
| Operating instruction | EN 13445-5: Annex C.5.7 | In- stallation, operation, and maintenance manual in acc. to Sect. VIII Div. 1 App. FF | In- stallation, operation, and maintenance manual in acc. to Sect. VIII Div. 2 Annex 4-B | In- stallation, operation, and maintenance manual in acc. to Sect. VIII Div. 1 App. FF |
| Certification | Pressurised Part: Certificate of conformity/3.1 EN 10204 | Partial data report | Partial data report | U-/U2 stamp Partial data report |
| Marking | Name plate: Identification of manufacturer; Identification of device; Operating parameters and temperatures; Note: CE marking is not required for this pressurised part | Name plate: U- stamp | Name plate: U2 -stamp | Name plate: U-/U2 stamp |
Applications of Quick-Actuating Closures and Quick-Actuating Closures
Quick opening closures are primarily installed on pig launchers and receivers, heat exchangers, pressure vessels such as filter units, strainers, scrubbers, autoclaves, and blowdowns on vertical vent stacks in many in many industrial sectors such as oil and gas pipeline, food industry, chemical industry, oil and gas industry pharmaceutical industry
