Internal Coating

The purpose of internal coating of steel pipes is twofold. In the case of natural gas pipelines internal coatings are in place to improve the flow efficiency of the pipeline. The internal coating reduces the pipewall roughness and thus friction factor. Due to the smoother inner surface the compressors needed to pump the gas through the pipeline can be reduced in quantity and size.

Second purpose of internal coating is purely for corrosion protection. Most pipelines used for transport of water or oils are coated nowadays with two component high build liquid epoxy linings to protect the pipeline during it's entire lifetime.

With over 50 internal coating plants in operation worldwide, Bauhuis International has by far the largest installed base of such plants.

In order to achieve the required coating quality, surface preparation prior to coating is essential. With the hydraulic powered turbine, which is one of Bauhuis most prominent designs, up to 500 m2/ hour can be blast cleaned to a S.A. 2.5 cleanliness value. For pipes smaller than 12" airblast stations can be offered.

Besides shot blasting and the actual coating most internal coating plants also contain stations for prewashing, preheating, blowing out, and finally curing. Apart from the most common liquid epoxy coatings Bauhuis can also supply plants for the application of cement mortar lining (mainly waterlines) and internal FBE (fusion bonded epoxy) powder coatings.

Specifications applied when designing the equipment are API 5LR2, AWWA C210-213.

The drawing below shows the standard design of an internal coating plant for liquid epoxy. By clicking on the cameras detailed pictures of the various equipment will be shown.