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Mechanical Interlock

Product Category:
Main Uses of The Product:

  • Used in Process Sequence Control Systems

  • Applied in Refineries, Petrochemical Plants, and Power Plants

  • Ensures Safe Operations for the Loading and Unloading of Hazardous Materials

  • Used in Gas, Steam, and High-Pressure Process Lines

  • Enhances Safety in Explosive Environments (EX)

  • Integrated with Lockout and Permit to Work Systems

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Product Introduction

Accidents in industries refer to events that do not occur frequently, but when they do, they can result in catastrophic consequences.
Start-up, shutdown, switching, and other examples of industrial operations are instances where small mistakes or lack of attention can
lead to undesirable and irreversible outcomes.

To prevent such incidents, our specialists have designed and manufactured a device called a mechanical interlock, which
controls the sequence of opening and closing material transfer valves.
To open and close transfer valves, control fluid flow, and perform maintenance on transfer lines,
the use of interlocks is essential to prevent unauthorized operations and
ensure the safety of pipelines and personnel.

In general, interlocks are used for the following purposes:

  • Compliance with procedures
  • Personnel protection
  • Equipment protection
  • Environmental protection

Interlock Function and Logic

A mechanical interlock is a combination of locks and keys that keeps valves in one or two positions (open or closed).
The interlock and its associated valve operate such that opening or closing the valve is only possible when both keys are inserted into the interlock.
In other words, the valve in its fully closed or fully open position has only one key and remains locked.

Using mechanical interlock systems ensures that equipment operates in a safe sequence and remains in a safe condition.
Interlocks not only control the sequence of opening and closing process valves but also prevent unauthorized operations.
Different types of mechanical interlock systems are designed based on the mechanism of key exchange.
In this system, valves can only be operated in a predetermined sequence to ensure production, safety, and accessibility.

Mechanical interlocks are typically installed on valves, gates, and rotary switches.

Technical Specifications

Legend Full-Rotation Lock Quarter-Turn Lock Material
1 Hand Wheel Sliding Lever Carbon Steel (Coated) / Stainless Steel
2 Body Body Stainless Steel
3 Linear Key Linear Key Stainless Steel
4 Key Slots Key Slots Stainless Steel
5 Connection Means Connection Means Carbon Steel (Coated) / Stainless Steel
6 Adaptor Adaptor Carbon Steel (Coated) / Stainless Steel
7 Bracket Bracket Carbon Steel (Coated) / Stainless Steel

Features Keys
Permanently Mounted on Valve Linear Keys
Suitable for All Hand Wheel Operated Applications. Uniquely Coded
No Grease or Other Lubrication Required Key Codes are Registered, for Easy Replacement and to Avoid use of Duplicate Keys
Entrance Protection of Key Slots by Self-Sealing Weather Strips
Single or Double Key Versions are Available.
Mounting Spare Keys Available
No Alterations to Host Valve Required Master Keys Available
Custom Made Bracket and Adaptor for Mounting to the Valve Colored Tag Marks
Original Nut is used if Possible Master Key & Master Key Cabinet
Can be Mounted in a Live Plant Keys are Inserted Linearly and the Internal Locking Mechanism Consists only of Linear Moving Components.
Can be Mounted on Each Size of Valve, However to a Maximum Valve Spindle Size of 68 mm. Above That Size, a Customized Interlock is Provided.

Industrial Valve Interlock System

  • Enhanced Operational Safety:
    Controls the sequence of valve operations to prevent human errors in critical processes.

  • Prevention of Unauthorized Operations:
    Lock-and-key mechanism ensures operations cannot be performed out of the approved sequence.

  • Compatible with Various Industrial Valves:
    Can be installed on ball, gate, butterfly, and other common valve types.

  • Compliance with International Standards:
    Designed according to API RP 553, OSHA, and IEC 61508 standards.

  • Corrosion-Resistant Body:
    Constructed from stainless steel or high-strength alloys, suitable for harsh industrial environments.

  • No Power Required:
    Fully mechanical operation, independent of electricity or control systems.

  • Customizable Design:
    Tailored to operational requirements, including number of keys, valve type, and operational sequence.

  • Easy Installation and Maintenance:
    Modular design allows quick installation and routine servicing without process shutdown.

  • Universal Valve Compatibility:
    With the “O-Ring Mad Sanat” adapter, a single interlock unit can connect to all valve sizes, providing a locally engineered and upgraded solution.

  • Choice of Operating Mechanism:
    Available with 90° lever or handwheel based on customer preference.

  • Lubrication-Free Design:
    No need for oil or grease, ideal for low-maintenance industrial environments.

  • Suitable for EX/Explosion-Prone Areas:
    Certified for use in hazardous locations, meeting explosion-proof safety standards.

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