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Double block and bleed valve

In order to ensure safe operation of double block and bleed valves, Alcatraz Interlocks provides quarter turn and multi turn interlocks, with both single and double keys in three sizes: small, medium (only quarter) and large. 

Double Block and Bleed valve Interlocks come in several variations depending on the type of Double Block and Bleed valves (DBB) and the requirements with regards to Interlocking them. By default both isolators are interlocked, optionally the bleed valve can also be interlocked. The initiating key from the control room or another Interlocked application is inserted into the first isolator interlock to be unlocked and closed, releasing its locked closed key which is used to unlock and close the 2nd isolator section of the DBB, the 2nd key is released and confirms the DBB valve is fully isolated, the key can now travel further to another application, alternatively it can be used to unlock and open the bleed valve to bleed any excess medium in the DBB valve.

Applications for double block and bleed valve interlocks

To offer the right interlock for a block and bleed valve we need to understand your application and sequence of actions. To execute this properly our dedicated team could assist you with measurement, commissioning and installation. Block and bleed are commonly used in applications like:

Download specs for Double block and bleed valve Interlocks

Solutions for interlocking double block and bleed valves

Since DBB valves come in all different sizes we often encounter DBB valves which are too small for our standard Interlock units, however being specialized in bespoke solution we design ultra-compact interlock applications to fit every DBB valves by using our Bolt Locks or our Lock Portions fitted on a custom designed mechanical device safely locking the DBB valve as per client requirements.

Multi and quarter turn interlocks specs:
  • AISI 316
  • Material certificate 2.1 (3.1 on request)
  • ML 1 interlock can be mounted onto all host valves with a drive bush edge to edge dimension less than 65 mm
  • Electropolishing
  • No modification to host equipment

Feature and benefits:
  • Integrated 90-degree end stops (quarter turn)
  • Mechanically programmed keys
  • Integral parallel splined drive-tube
  • Encapsulated lock portion preventing ingress & contamination
  • Alcatraz 5 step safety integrity design

Our specialists

Meet specialist Dennis

Do you want to operate safely and prevent failures in your applications? Contact Dennis or one of our technical engineers to discuss how to do it.



Do you want to receive more information about our custom-made valve interlocks and trapped key solutions on your application? Please fill in the contact form and we will respond as soon as possible.


Electrical Key Cabinets

An Electrical Key Cabinet consists of integrated electromechanical components preventing key removal.

Spare Keys

The spare keys are intended to briefly replace a lost key until a replacement has been purchased.

Sequence control units

This is a mechanical device that is designed to fulfil client's complex non-linear Interlocking Sequence requirements.