Coatings, CVD, PVD

DAL has been applying protective coatings to the Oil & Gas, Chemical and Petrochemical industries for many years. Principally we offer the following:

  • Aluminide diffusion coatings: for protection against metal dusting, hot corrosion, oxidation, carburisation and sulfidation
  • Chromide diffusion coatings: for protection against hot corrosion, carburisation and sulfidation and wear
  • Boride diffusion coatings: for protection against rod wear, erosion, abrasion and corrosion issues

Unique coating capabilities: Due to our range of furnace capabilities, DAL can process an unparalleled range of component sizes which can be extremely useful for the complex processing plants of our Oil & Gas and Process customers. We can process components a from a few millimetres in size to components up to 18.5 metres long, 3 metres in height and 4 metres in width.Our proprietary pack process also allows us to process complex parts and restrict the areas of diffusion coating, through masking off, if required.We process at our two facilities in the UK. Smaller components we process in Hatfield and long tubes and large components in Teesside, Middlesbrough. Our furnace in Middlesbrough is we believe the longest coating furnace in the world.

Aluminising: protection against metal dusting

Commonly, customers approach us that have a problem with metal dusting. Metal dusting is a catastrophic corrosion phenomenon that leads to the disintegration of structural metals into dust composed of metal carbides and carbon.Aluminide coatings protect from metal dusting both by being highly resistant to corrosion themselves and by reducing the diffusion of carbon into the base alloy by orders of magnitude. Aluminide diffusion coatings also show good resistance to spalling caused by thermal cycling, having been extensively applied to gas turbine components.Detailed studies have repeatedly confirmed that pack aluminide diffusion coatings are a highly effective way of protecting components from metal dusting corrosion.We aluminise large and small, including long tubes up to 18.5 metres in length, spools, ferrules, fasteners and burner plates for our customers.We aluminise for a range of processes that experience metal dusting conditions including steam methane reforming, gas and steam reformers in ammonia production, steam reformers for the direct reduction in iron ore, syngas production, hyco production, methanol production and petroleum refining.

Aluminising: protection against sulfidation, oxidation and carburisation

Pack aluminide coatings also provide impressive resistance against a wide variety of corrosion problems particularly oxidation, carburisation and sulfidation in high temperature environments.Commonly we see aluminising being used for protection in steam-methane reforming (SMR), methanol production and for gas desulfurising processes (the Claus process).Aluminised components include heat exchangers, combustor tubes and condensers.

Boronising: resistance to abrasive wear, high hardness

Boronising, sometimes referred to as boriding, is a diffusion coating with a low co-efficient of friction that is capable of retaining its high hardness at elevated temperatures. In the Oil & Gas industry it is most typically used in down bore drilling casing tubes where CO2 corrosion, or ‘sweet corrosion’ and wear damage can be the significant contributing factors to degradation of the casing tube. Boronising is also used to create a hardened bearing surface on drill bits utilised for deep bore holes as well as valve stems.It can be applied to a wide range of alloy steels and in addition to its very high hardness it improves the alloy steels resistance to oxidation, hydrochloric, sulphuric and phosphoric acids.At DAL, we have the flexibility to boronise a wide range of component sizes.Typical materials for boronising casing steel grade tubes in the Oil & Gas industry include API 5CT specification:

  • Carbon steel – J55 & K55
  • Alloy steel – P-110

DAL boronises a wide range of materials for other industries.

Chromising: an alternative coating for Type II corrosion environments

Our chromide diffusion coatings can be an alternative to an aluminide coating especially in Type II hot corrosion environments. Steels with a carbon content of greater than 0.3% will when chromised form a hard dense diffused chromium carbide surface layer which has a high hardness and excellent wear resistance in hot, corrosive environments.Types of components we would typically chromise for the Process industries include tubes in recovery boilers used in the Kraft Process.As with aluminising, we have the flexibility to chromise a large range of different component sizes.