Product category:
Alarms, annunciators and safety interlocks
News Release from: Smith Flow Control | Subject: Key-exchange interlocks
Edited by the Processingtalk Editorial
Team on 03 April 2003
Key interlocks for safe pig trap
operation
A key-exchange interlocking system from Smith Flow Control has been designed to control the safe operation of Pig Trap closures, eliminating any possibility of human error or deliberate abuse
It forms part of a comprehensive range of safety systems specially designed for both the on- and off-shore hydrocarbon and chemical processing industries It is widely acknowledged that the single greatest hazard associated with accessing pressurised vessels such as Pig Trap closures is the risk of opening the closure while the vessel is still pressurised or contains residual hazardous product
This article was originally published on Processingtalk on 24 Feb 2003 at 8.00am (UK)
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For this reason the only reliable way to prevent the possibility of unsafe opening is to interlock the Pig Trap opening mechanism with the vessel vent and/or drain valves.
The principle of the key-exchange interlocking system is very simple.
When work needs to be carried out on an interlocked Pig Trap, a specially coded permit key is issued from the control room.
The insertion of the permit key into the first valve of a sequence unlocks the valve assembly, allowing operation of the valve.
When the valve has been operated to its new position, it may then be locked by the removal of a previously trapped second key.
This key is coded in common with the next designated valve lock in the sequence and the procedure is repeated until the vessel has been totally isolated, vented, drained and purged.
This ultimately releases the closure lock key (usually after locking open the vent valve).
Loading or retrieval of pigs can therefore be carried out in totally safe conditions and, by reversing the interlocking procedure, the vessel can be re-pressurised and restored to normal operation.
The interlocks are manufactured from AISI 316 Stainless Steel and have a sealed-for-life lock body with self-sealing internally fitted weather-strips in key entry apertures.
They are factory lubricated prior to final sealing and require no further maintenance.
The tamper-proof 'coded-card' key design also eliminates any possibility of unauthorised operation using forged keys or other implements.
Smith Flow Control is the world leader in process safety systems and can provide a turn-key services from initial consultation through to installation and commissioning. Request a free brochure from Smith Flow Control ...
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