Flange Separation

Previously when flanges were fused together due to corrosion, rust, age or internal friction, or were difficult to split apart due to a lack of lifting or pulling power, there was – put bluntly nothing much anyone could do without incurring huge expenses, work stoppages and costly delays.

Unique Splitting & Separating Service

ThinJack® is a unique splitting and separating service that effectively separates well flanges. The ThinJacks themselves are usually curved steel envelopes less than 3mm thick which are inserted between the 2 items for separation.

They are often made to fit between the flange’s bolt holes and the outer edge. When inflated, ThinJacks start to become cylindrical. The inflation means that the 2 parts of the flange are pushed apart, in a controlled manner, drawing rusty bolts through the flange bolt holes at the same time.

ThinFlate is the bespoke hydraulic inflation system providing up to 36 250 psi (2500 bar) pressure which creates the ThinJack force of up to 2.5 tonnes per square centimetre of ThinJack area. 


In using this method hundreds of tonnes of controlled force is applied exactly where the force is needed. The flange binding force is caused by:

■  Rust in the bolt hole annuli.
■  Rust between the ring gasket and the inside of the bolt holes.
■  Seal friction in the flange bore.

The Service Summary is

About the ThinJack separation service

The ThinJacks themselves are:

■  Designed to meet specifications for API 6A flanges.
■  Engineered for custom applications.
■  Made to any flat shape and some 3-dimensional shapes. 

Why is the service used?

■  For delivering hundreds of tonnes of controlled force at the place where the force is needed.
■  Where conventional pulling or separating systems are not suitable or unavailable.
■  Where the drill string or crane has an insufficient pulling force to safely separate the flange.
■  Where the floor or deck or structure condition cannot carry a crane or a conventional high force jacking system.

What is delivered?

■  A controlled force that is significantly higher than from conventional hydraulic spreaders or the pulling-power of drill strings.
■  Separation in any direction.
■  Jacking within gaps with a service that is an order of magnitude thinner than any other system.
■  Controlled and even flange separation, ensuring the flange studs do not become tilted and jammed inside the bolt holes.
■  An intrinsically safe, alternative to cutting and grinding tools.
■  A rigless and crane less service, though some of our work is enhancing the pulling limitations of drill strings.

With these advantages invariably delivered:

■  The service reduces the chance of injury to people or damage to well equipment. It avoids:
 - Jack and sledgehammers and wedges damaging gauges and Inconel piping. 
- An uncontrolled pull or jump of the XMT damaging the hanger.
■  The service usually eliminates the need to cut bolts or studs, meaning that the flange may be re-connected partway through the separation if your well barriers are not quite as good as you had thought. Yes, it happens…
■  The risk of damage to flange faces during the separation process is greatly reduced.


Where a significant force is needed at specific locations on a seized flange, ThinJack delivers hundreds of tonnes of controlled force safely and precisely. This is a service package with less disruption and customer application engineering than other methods.

Force and stroke

ThinJack Force. The Sum:

ThinJack force is calculated, in Kilogrammes, from Force = Hydraulic Pressure X Area, where pressure is in bar and the single-sided ThinJack area is in square centimetres.

ThinJack Force. Analogy:

If you press down with a pressure of 1 bar on a ThinJack which is the same area as the 1 centimetre by 1 centimetre size of your fingernail you will press with a force of 1 kilogramme. That is the same force on your fingernail as atmospheric pressure.

If you increase the pressure to 2500 bar, you will press with a force of 2500 kilogrammes or 2.5 tonnes. That is the same force on your fingernail if it was in a water depth of 25,000 metres.

ThinJack Force. Reality:

A ring of 3 ThinJacks, inside the circumference of a 13 5/8” 5M API 6A flange have a typical area of 244 square centimetres (38 square inches). If we pressurise the inside of the ThinJacks with 2000 bar (29 000 psi) the ThinJacks will create a force of 488 tonnes. (Approximately 1.1 million pounds).

ThinJacks will create the force needed to separate a stuck object using up to 2500 bar (36 250 psi) of hydraulic pressure. Invariably, the fluid volumes are small and there are a number of overlapping control measures in the service procedure to mitigate any residual risk.

ThinJack Stroke:

We intentionally destroy the ThinJacks to get the maximum possible stroke. The potential stroke of the ThinJack is limited by its width and the pressure on the inside of the ThinJack. Once used, ThinJacks are replaced by others and the gap is packed with matching ThinShims, until the flange binding force is less than an available separation system with a high stroke.

High Stroke and Low Pulling Capability:

Once the binding forces of the flange are reduced to the push or pull capability of any high stroke system available, we use these to complete the flange separation. These high stroke systems can be conventional flange spreaders (say 20 tonnes) and supplied with our service; a crane (say 30 tonnes); drill string (say 90 tonnes); lifting frame or chain block. Usually lifting frames and chain blocks are restricted to the weight of the flange or XMT. That is, they lift but not pull.

Higher Separation Stroke

The wellhead lifting frame is for lifting XMT's separated by ThinJack services where there is no crane or drill string to pick up the separated XMT. On this rigless project the concept, overview and operational procedure was initiated and prepared by ThinJack Ltd with others contracted for the detailed design and manufacture.  See the picture to the right.