The Emerging Use of Digital Technologies to Support Mechanical Interlocking Valve Processes

29 January 2016

Single Point Control

Eni Norge, part of the globally operating ENI group,  is an energy company in oil & gas production and one of the major operators on the Norwegian continental shelf. To enhance safety and protect its operators, Eni Norge looked to simplify its valve processes by moving the control and operation of its large number of valves to a single, safe location. Eni Norge approached us to solve the problem and this led to the development of the custom-built operating panel.

The electronic operating panel aggregates all single valve control points away from the local site into one graphical system. The panel works as a communication and verification system and enables an operator to control a sequence of actuated valves directly from the panel. Although the operating panel can be used in a wide variety of applications, in this case the panel was specifically designed for use with a pigging procedure, and two panels were installed on an FPSO built for use in the Goliat Field, the first oilfield to be developed in the Barents Sea. Each panel controlled four valves.

Designed around the requirement to isolate power to the panel, the operating panel incorporated two interlocked key units to ensure a specific sequence of operation:

  • The operator selects to close the valves as required
  • Red LED lights verify that the valves have reached their fully closed position
  • When all valves are closed, the operator can isolate the panel by removing the ‘A’ Key
  • The ‘A’ key is then entered into the solenoid key unit and only when the safety and automation system also confirms all valves are closed, a permissive signal is sent to energise the solenoid and release the ‘B’ key
  • This allows the operator to safely continue the mechanical interlocking sequence and, in this instance, only after the panel has been isolated and all the valves have been closed and locked, will the final key be available to manually unlock the pig trap door to load or unload a pig.

Valve Operating Panel

Two-Tier Safety System

In the process industry, mechanical interlocks guarantee strict adherence to procedures and help avoid human error. They are particularly useful for highly dangerous operations such as pigging and valve changeover procedures.

Risk factors that contribute to pipeline pigging incidents include a lack of operator training or complacency, a lack of hazard awareness or workers relying solely on pressure gauges creating a false sense of security.

Interlocks ensure extremely high levels of safety by guaranteeing that valve operation sequence occur in the correct, safe order. However, they usually function as stand-alone safety systems. A serious incident during a pipeline pigging process highlights the importance of moving towards the integration of digital technology into traditional safety systems for a two-tier safety system.

Two workers were attempting to remove a pig from a line launched the previous day but found the pig stuck in the reducer section of the pipe. It had passed the main block valve so the valve could be closed but remain wedged in the entrance. The workers depressurised the pig receiver in standard, safe working practice and opened the vessel door to the atmosphere. It was assumed that the energy has been removed. However, when the workers attempted to remove the pig by attaching a length of stainless steel tubing, the pig shot out and struck one worker on the nose, resulting in major facial injuries. On review, it was found that the pig had created a temporary seal with a weld in the reducer section and created a pressure trap behind the pig. Once the operator attempted to manually move the pig, the pressure blasted the pig out of the receiver at high speed.

During such a pigging operation certain safety conditions need to be met: as the example above shows, the vessel pressure should be at a safe level and all dangerous gases and residue must be removed before opening the pig door. Mechanical interlocking guaranteed that all required valve operations were performed as outlined, but the accident still occurred. The process industry’s preventative actions outline that along with risk assessment and hazard identification and the proper training of personnel, there must be procedures in place to address both the normal and upset conditions on the ground.

This has led to the development of SmartTrap+, which combines digital technologies with traditional interlocking. SmartTrap+ incorporates signals from other field devices like pressure or H2S/CO2 sensors into the interlocking sequence, and only releases keys for mechanical interlocking if all conditions in the process have been met. It offers the highest level of process safety by offering proof.

SmartTrap for Pig Trap Interlocking

For example, opening and closing a vent valve does not give real time information that the vessel pressure has actually reached a safe level; while opening and closing a drain valve does not guarantee that all residue has been removed. By incorporating pressure signals and SmartTrap+ into the interlocking sequence, interlock keys can only be released if the pressure in the pigging system has been equalised. This would mean that SmartTrap+ would detect pressure build up in the pig receiver and refuse access to  vessel closure door; the key to the vessel door will only be released when the pressure inside the vessel is acceptable and no dangerous gases or residue are detected. SmartTrap+ provides electronic confirmation of sensors across the process; it reduces the need for operators to climb up and down ladders across the site to manually confirm all signals and reduces the scope for operator error.

SmartTrap+ has taken the single-point control concept a step further by delivering real-time information into the process. SmartTrap+ can work in conjunction with the operating panel to offer full, safe control over dangerous processes.

Real-time Management

The implementation of RFID (radio-frequency identification) technology is an increasing trend in the oil & gas industry. RFID tagging gives the ability for real-time monitoring of processes as tagging pipeline components can register faults and deliver maintenance history to keep processes moving. RFID technology allows the track and trace of products and this has been utilised by operating companies to ensure safe interlocking sequences.

Using a key management system with RFID provides an enhanced level of system security for mechanical interlocking keys. Statoil, the largest oil and gas operator on the Norwegian continental shelf, includes a requirement for electronic key cabinets in its governing document that covers the technical requirements for valve position securing systems for safeguarding and maintenance. It states that an electronic key cabinet system will include key panels and key tag readers, electronic ID tags and system software. It is important that such a system is ‘future-proofed’, allowing for the expansion of systems without overhauling the current installation.

A huge benefit in using RFID in this way promotes operator accountability and improves worker performance. For example, with SFC’s SmartKey+ management system, all keys are trapped in the cabinet and only authorised personnel are able to gain access to the keys appropriate to them. This system again reduces the burden from the worker at the local site. Keys can be tracked in real time, providing the operator and control room personnel with information on interlocked processes and their statuses; a full transaction history is available. This can ease maintenance work by providing a reviewable process of key activity and frequency of use. It also uses license-free software that enables systems to be expanded without significant expense. Also, the ability to retrofit RFID tags into existing key systems already in use means that safety systems can be quickly brought up to date.

SmartKey+ Key Management

The user is identified by a unique access code and once authorised, selects and removes the appropriate ‘initiating’ key from the panel as the selected key position is indicated and unlocked. The worker can then use this key to start the mechanically interlocked process in the pre-defined sequence. Once completed, the user scans the key in front of the scanner and returns it to the appropriate, highlighted section.


Operating companies have recognised that the integration of digital technology with mechanical interlocking provides multiple benefits.

Firstly, the safety of the operator is paramount, and integrating digital technology reduces the burden from the operator at the local site. It enhances safety by providing umbrella control over dangerous and complex processes. This extra layer supports the traditional use of mechanical interlocking by providing communication and proof of ongoing valve operations.

In addition, complex processes often benefit from incorporating digital technologies by boosting efficiency. The single-point control can streamline a process that often includes multiple valves and hazardous manoeuvres. Workers can feel supported by the two-tier safety system and, as in the case of SmartTrap+, no longer need to seek out manual confirmation of sensors and signals around an interlocked process, which can lead to human error.

RFID technology offers real-time monitoring of key movements during dangerous valve processes. It leads to improved inspection and maintenance by offering reviewable data that reduces downtime and associated costs. This has the knock on effect of increasing worker accountability and improving operator performance.

The emergence of electronic technology is the natural progression of the industry. It works to support the traditional method of interlocking valve operations and together they enhance safety and streamline processes, a win-win.

Putting Safety First when Operating Couplings

4 November 2015

Couplings are used to rapidly connect and disconnect fittings on piping and hoses and are frequently found in a wide variety of demanding industrial environments. Applications may include, but are not limited to, tank and transfer systems in the oil, gas and petrochemical markets, pipelines, shipping, transportation, water, power generation and the food and beverage industry.

The market is saturated with couplings, which can make the decision making process quite challenging. However, one of the most important considerations when selecting a coupling device is identifying a product to match its intended purpose and application parameters.

Bajolock Product Series

(Above – Bajolock® range – The ultimate safety solution)

As with all mechanical devices, identifying the most suitable product for a particular process is a pivotal factor. Nevertheless, many decisions are often based around price rather than performance requirements.  This is one of the most common sources of error in the selection of suitable couplings.  Consideration should be given to various performance factors:  A design engineer must address issues such as the application environment, criticality, serviceability, maintenance, and speed of replacement if required — as downtime can seriously degrade many processes.

Driven to reduce costs, engineers may shortchange the application by being overly thrifty in their coupling choice. While this approach may reduce upfront component costs, extensive and expensive backend warranty claims can greatly compromise an OEM’s bottom line and product reputation.

Smith Flow Control’s recently launched Bajolock®, boasts a patented, novel and innovative design and has undergone extensive product testing and development. Safety is of paramount importance; the operator is placed at the heart of the design, with user interface and user experience all important considerations.

As a result, Bajolock® incorporates unique features that make it impossible to compare it to standard coupling devices. Bajolock® is distinctly different from other couplings and has been awarded a patent for its novel engineering: This protects the ornamental aspects of the design and at the same time, installs the greatest confidence in operators that use it.

In absence of a manometer, it is often impossible to determine (residual) pressure in the system and fatal accidents may occur. Therefore, conventional couplings are very dangerous when opened in pressurized conditions.

Bajolock Lock

(Above – Standard couplings with minimal safety features)

Bajolock Couplings Under Pressure

(Above – Plug projected under pressure with standard couplings)

Bajolock® prevents serious operational incidents. Unlike other couplings, the plug is prevented from projecting under pressure as it is captured in the interface. Bajolock® features additional openings (ventilation slots) to enable pressure and product release.  Any pressure is discharged away from the operator in a controlled manner.

Close up of Bajolock Coupler

(Above – Bajolock® open, pressure is dissipated and plug prevented from projecting)

Bajolock® can be easily and safely disconnected with a short twisting action and rejoined with ease, making it the safest solution available and greatly minimizing the possibility of operational incidents.

For more information contact@


A Bio from our new FD

29 October 2015

Hi everyone, and first of all, thank you all for the warm welcome I have received.

A little bit about me!

I spent the first 10 years of my career in public practice with Price Bailey, a local firm of Chartered Accountants. Whilst there, I completed both my AAT and ACCA studies. Since then I have spent the last 17 or so years sitting on the other side of the fence, plying my trade in industry and commerce, and have held a number of finance roles ranging from Financial Accountant to Group Finance Director.

I have held positions with both locally established family run businesses and larger corporate entities based in The City in a variety of different industry sectors (Stock photography, Telecoms, Life Sciences and a Professional body for Facilities Management). Naturally, I have always run the Finance department, but additionally, at one time or another, I have had responsibility for the majority of back office supporting functions.

I live in Bishops Stortford with my wife Emma, three children Luke, Ben and Holly and Labrador Bella. If I am fortunate enough to get any free time, I try to get out on my road bike, though these days my legs don’t go round quite as fast as they used to!

I am really excited about the challenge ahead of me as Interim FD, and I look forward to working with you all over the coming months.


Mark Morgan Photo_edited-1

Smith Flow Control Appoints Business Area Manager

2 October 2015

Valve safety company Smith Flow Control (SFC) has appointed Peter Wall as its new Business Area Manager. Peter is based at SFC’s office in the Netherlands which is responsible for the sales and technical support of Smith Flow Control’s safety products in Europe.

Peter has previous experience working with safety interlocks, having worked for two years as Sales & Marketing Support Engineer with CEF Safety Systems.

Peter commented: “After working for CEF Safety Systems in the late nineties, I’m very happy to get this great opportunity to be involved in the industry again. I think SFC has very unique and world class products in an ever changing market with huge possibilities and potential. I’m looking forward to being part of the team and making a difference.”

Mike D’Anzieri, Managing Director at Smith Flow Control, said: “We welcome Peter to SFC. He has had the opportunity to work in different industries and he can bring real insight and a fresh perspective to Smith Flow Control. We’re really looking forward to working with him.”

Smith Flow Control appoints new Regional Business Manager

Moving Away From Mechanical – Developing More Sophisticated Products For Our Clients

26 August 2015

SFC’s traditional key cabinet range simply offers a visual representation of systems and their status from a Control Room environment. With RFID Cabinets, management teams and key operational staff are able to identify exactly who, what, when and the full status of a given system, anytime, anywhere, simply be accessing a remote interface. Digital has revolutionised the way in which data can be shared and dispelled, simply by logging on remotely. This innovation supports the reorganisation in workforce operations, progressively common in the oil and gas industry. Remote working is becoming increasingly desirable, with digital technologies facilitating this. Real-time reporting based on RFID helps offer the customer a level of accuracy and intricacy, which is far removed from traditional key cabinets.  Download the full Data Sheet here

SmartKey+ Product Innovation


Pipeline Safety and Security – the Role of Key Interlocks

18 August 2015


Pipeline operations in the oil and gas industry are safe if carried out correctly but can have catastrophic consequences if performed incorrectly, particularly if high temperature, high pressure or toxic/flammable product is present.

The industry generally has a disciplined approach to pipeline design and operating practice, governed by recognized international standards and enforced by regulators and certification authorities. While good practice begins with good design, both are inevitably hostage to the ‘human factor,’ which is responsible for 70 percent of all reported incidents and accounts for 90 percent of financial loss.

Human Factors Engineering (HFE) is the design of work processes and systems to ensure the safe and efficient functioning of workers by taking into account human capabilities, limitations and requirements.

Pipeline valve systems must be designed for safety rather than placing sole responsibility on the operator. Distractions, misunderstandings, shift changes or simple accidents can all lead the operator to make catastrophic errors. Simply relying on operator adherence is not enough – safety must be applied to the process itself. The focus then becomes accident prevention, not accident management.

Mechanical Interlocks

Mechanical interlocks remove the ‘human factor’ by ensuring dangerous processes happen only in a designated sequence. They are simple mechanical locks designed as integral-fit attachments to the host equipment such as valves and pig traps – any equipment needing human intervention. Workers transfer specific keys from lock to lock (equipment to equipment) in a particular sequence. Each step in the process is only possible after the previous step has been completed and the sequence must be followed in the exact order to completion.

An interlock is essentially a dual key device that locks the host process equipment in one or more conditions. The standard condition is with one key trapped in the interlock and the valve is locked in status ‘1’ with the second key elsewhere. To operate the valve to status ‘2’ the second key is obtained from a control room and inserted into the interlock. The valve is then operated to status ‘2’, releasing the initial key and trapping the second one. The released key can then be used to operate the next valve in the sequence or returned to the control room if this is the end of the sequence.

When not in use the initiating key for each system should be kept in a locked key cabinet in a control room, with visual status indication at all times.

Mechanical interlocks are ideally suited to integrate with permit-to-work procedures. The Cullen Report on the Public Inquiry into the Piper Alpha Disaster (1990) strongly recommended the use of locking systems integrated with permit-to-work procedures, especially where routine procedures cannot be accomplished in the time-scale of a single work shift. They ensure safety, rather than place responsibility on the operator. Well-designed key interlock systems are always operator-friendly – they require no additional effort than normal procedures would require and, most importantly, should never permit more than one key to be free (available) at any one time.

Primary and Secondary Safety Systems

Whether a pipeline or process module is of simple design, with basic functions controlled by manually-operated valves, or of complex design controlled by sophisticated mainframe Distributed Logic Control (DLC) systems; key interlocks can provide a totally reliable mechanical assurance of safe operating practice in which the operator’s scope for error is eliminated.

Within DLC controlled systems, which invariably incorporate electrical interlocking (‘trips’), these are usually limited to governing only the operation of high-criticality motorized valves. Associated miscellaneous services valves (e.g. for venting) may be manually-operated valves and will therefore not be recognized by the DLC management system. Correct operation of these valves may still be critical or semi-critical and may be dependent solely on the operator following written operating instructions.

In DLC-managed systems, key interlocks can form a vital link between managed and unmanaged valves. In these circumstances, the key interlocks are not intended as the primary safety system but as a secondary back-up system to the primary (DLC) system. Designs have been developed in recent years to provide key interlocks that offer the only total form of interdependent control over the operation of motorized and manually operated valves in one fully integrated system. When applied to motorized valves, the interlock design ensures that the failsafe function of the valve is never compromised.

In process systems where the valving and/or control components are all manually-operated (i.e. not DLC controlled), key interlocks become the primary safety system. They are particularly suitable as the primary safety system for remote locations where power is unavailable.

Typical Specifications for Valve Interlocks

Valve interlocks should be used in the following situations:

  • Where it’s possible to isolate a relief valve by means of a block valve
  • Where it’s possible to isolate the flare system
  • To ensure that a pig launcher or receiver is properly depressurized, vented and drained before the closure is opened and that no line valve can be opened when the closure is open
  • For process reasons

All interlocks should adhere to the following:

  • They must be suitable for use in external, industrial environments that also may be a corrosive, tropical, desert or marine location
  • They must be durable, robust and easy to operate with gloves
  • They should be 316 stainless steel for strength and corrosion resistance
  • The internal mechanism should be free from galling and lubricated for life
  • All key entry points should contain a device to prevent the ingress of dirt and water
  • They must be fitted to the valve manufacturer’s standard supply valve without any alteration to the valve except to remove or modify the valve handwheel or lever
  • They should be suitable for installing on an inline valve
  • All special tools for installing, commissioning or adjustment of interlocks should be supplied with the interlocks, along with simple graphical installation instructions
  • They should be maintenance-free and tamperproof
  • The interlock body must be stamped with the appropriate tag number and tagged with the applicable key codes and reference letter
  • As the interlock replaces the original valve operating lever or handwheel, it should be supplied with the nearest available lever or handwheel size to suit the interlock
  • They must be coded to provide the operating sequences specified in the material


  • Operating keys should have a colored key tag bearing the system tag number and the key code reference
  • The key should be 316 grade stainless steel or better
  • It should be impossible for an interlock to be inadvertently operated by a key not coded for use with that interlock
  • The key shall be easy to use even with gloves.
  • With the exception of the system initiating key, which is held in the control room key cabinet, all other system operating keys will be trapped in their respective interlocks
  • At the owner’s discretion, spare or duplicate keys can be provided. These should have strikingly different colored key tags to any other keys on site

Key Cabinet

  • The control room initiating key cabinet should be lockable and fitted with a synthetic glass window to allow easy visual assessment of the status of all of the interlock systems
  • Each interlock system should have its own dedicated position, bearing the system tag number and revealing “Work in Progress” when the key is removed
  • The color of the cabinet tags should contrast with those of the key tags
  • Key cabinets should be made from mild steel suitable for a protected indoor environment
  • If spare or master keys are required they should be housed in separate, lockable key cabinets with solid doors and contrasting cabinet tags

Smart Key Cabinets 

Pigging operations are particularly dangerous, as opening a pig trap closure while there is pressure in the barrel can shoot the pig out of the launcher at high speeds. Attempting to pass a pig through a partially open outlet valve, or prematurely opening the pig trap in the presence of high levels of toxic hydrogen sulfide, can cause fatal consequences. There are a few simple steps to launch a pig safely using key interlocks. Each step traps and releases a key and can only be performed in a particular order. To begin with, keys are used to unlock and open the vent and drain valve respectively. These actions release a key that can then be used to open the vessel door safely and load the pig. Once the pig is loaded and the vessel door is closed and locked, a key is released to close the drain and vent. This action releases the key that opens the kicker valve and launches the pig. Once the pig is launched, the trap is re-isolated by closing and locking the mainline valve. This releases a sequence of keys that depressurize the trap by closing the kicker and opening the vent and drain. The final steps involve closing all valves; the final key is returned to the control room key cabinet where is it kept until the process starts again. No steps can be by-passed in this sequence, nor can steps be taken out of order. This simple, failsafe process ensures accidents cannot happen.


The global trend of contracting out site operations inevitably translates into the ‘casualization’ of labor, which in turn leads to an increased risk of accidents through human error or deliberate violations.

Well-designed interlocking systems can mitigate these risks – either by eliminating error or by greatly inhibiting the potential for violations. They should always be operator-friendly,require no additional work effort from the operator than normal procedures would require and, most importantly, should never permit more than one key to be free at any one time. The message is, ‘keep it simple.’

Can Smith Flow Control’s valve interlocks be manually adjusted?

19 May 2015

After a period of use, the closed position on Gate and Globe valves may have altered by as much as 1½ handwheel turns.  The difficulty then arises when the valve is shut tight, the interlock (closed) key will not release because the valve has travelled past the original set key release position.  In these circumstances, the SFC ‘GL’ Interlock can be adjusted in-situ using a simple 3mm Allen Key.

The adjustment procedure simply involves operating the valve back to the original key release position – At this point, the lock datum set screws are aligned directly underneath the cam cover. Using the special tamperproof tool provided, the cam cover is removed to expose the datum set screws which are eased using a conventional 3mm Allen Key. The valve is then operated again to its shut tight (closed) position and the datum’s are retightened in the new position.  This In-situ adjustment feature is unique to the SFC ‘GL’ interlock assembly.

How to operate valve interlocks from the locked closed to locked open position?

15 May 2015

In process interlocking applications, sequential operating control is dependent on the interlock function of trapping and releasing the appropriate keys relative to the position of the host valve (i.e. open and/or closed positions). Typically speaking, Smith Flow Control provides mechanical interlocks with one key free and one key trapped.

SFC’s valve interlocks have two aperture points, designed to receive the interlocking keys, which change the state of the valve (open or closed). When the key is trapped in the left side, (looking directly at the key aperture points), the interlock is in the locked closed position (i.e. the valve is closed). When the key is trapped in the right aperture point, the valve is locked open. Insertion of the keys enables rotation/movements of the valve operating handwheel or lever.

What is EasiDrive?

13 May 2015

Smith Flow Control’s EasiDrive is an efficient and cost effective valve operating system.

EasiDrive can be used where valve size, pressure rating or work environmental conditions would normally demand a permanent, dedicated actuator or would require a work crew.  Designed to operate in/with minimum facilities, EasiDrive is available in three options – pneumatic, electric or battery, with the most popular choice being pneumatic, running off of plant air.

EasiDrive is fully portable and can be supplied to manage any single valve or a bank of valves. The system consists of three elements – drive tool, valve coupler system and a power pack. All torque ranges are supported, with variable torque adjustment as standard.

Check out our video

What is FlexiDrive?

13 May 2015

FlexiDrive is a unique cable driven remote valve operator, which enables valves and other wheel operated devices in remote, hard-to-reach or hazardous locations to be operated with ease from a conveniently located handwheel.  Remote valve operation is encouraged in many Human Factors Engineering Specifications.

Check out our video.