Gold plated metal seals for Oil & Gas couplings Our customer designs and manufactures hydraulic distribution products and systems. These are used to control subsea production systems for the offshore energy industry globally. We explore here how our gold plated metal seal solution suited the application due to its malleability and suitability for slightly dynamic operation. … Continued
Why use metal seals? Using metal seals as an engineered sealing solution is appropriate when it’s not possible to use elastomeric or polymer seals. This will be because of extremely demanding application requirements. For example, these could include applications with extremely high temperatures (300°C upwards) and pressures, intense radiation, cryogenic conditions or highly aggressive chemicals. … Continued
Using metal seals as an engineered sealing solution is appropriate when it’s not possible to use elastomeric or polymer seals. This will be because of extremely demanding application requirements. For example, these could include applications with extremely high temperatures (300°C upwards) and pressures, intense radiation, cryogenic conditions or highly aggressive chemicals.
The metal seal concept is based on plastic and elastic deformation of the seal during compression which creates a sealing interface. The metal seal is compressed in the cavity on average about 20% of its original free height and the force generated through compression of the ring produces a high contact stress at the seal/cavity interface. This force is then supplemented by the pressure-energisation force which rises in proportion to the increase in differential pressure inside the seal cavity.
There are three types of seal energisation; self, spring and pressure energisation. By design metal C-rings are self-energising due to the good spring back characteristic of the C-shaped profile. They can be used in internal, external and axial pressure conditions. There are different base material characteristics and heat treatments, along with material thickness and cross section of the seal. These all determine the compressive load and is directly related to the sealing level achieved and is known as “self-energisation”. Spring energised seals have excellent spring back properties and are typically used to improve leakage rates by increasing the load on the sealing interface.
All metal seals can use system pressure to generate a hydrostatic load to obtain the highest level of sealing possible. This is known as pressure energisation. At high pressures this becomes an advantage and allows the design of metal seals for applications of 25,000 PSI and above.
Once the metal seal profile and material have been selected (depending on the application), a variety of platings and coatings are available. This is to modify the surface properties of the seal to create a malleable outer surface layer. Typically, precious metals such as gold and silver are used for plating. However, many other options are available with two common ones also being Tin or PTFE. This layer ensures optimum sealing despite any mating surface imperfections. The plated or coated layer also reduces coefficient of friction so the seal can slide and bed down during initial compression, therefore preventing galling. As well as providing better physical properties to the seal, coatings and platings are chosen to withstand high temperatures and aggressive (often corrosive or oxidizing) environments.
With ever changing industry demands and fast paced technology developments – particularly from our customers in the Oil & Gas, Aerospace & Defence and Automotive markets – we are challenged daily with applications where the boundaries are being pushed to the absolute limit. We’ve designed metal seals into F1 car exhaust systems, subsea repeaters, oil and gas production valves as a few examples. The capabilities of high-performance metal seals are endless. Working with the latest developments in materials, platings and manufacturing technology; our engineering team design the sealing solutions to meet the complex specifications these types of application demand.
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