Sandblasting for Control Valve

[Euclyd]

Is it possible to do sandblast method for control valve? Typically 10 inch ball valve, with WCC steel body material. The reason is for removing rusts (corroded area to be clean) and do repaint.

Thank you for the response.

 

[moltenmetal]

There is no problem sandblasting any valve for re-painting, assuming you thoroughly protect or preferably remove all items that might be damaged by the sandblasting.

 

[Euclyd]

Thank you moltenmetal. But what if valve body only? Should I worry for damage, i mean what will it affect the thickness of the material?

 

[moltenmetal]

The corrosion has already affected the thickness of the material and will continue to do so unless you stop it by properly re-applying the coating to a clean surface. The sandblasting will remove only the corrosion and a minimal amount of clean metal underneatho. If the body is so thin that it has no corrosion allowance whatsoever, then it needs replacement- but who would specify a material subject to exterior corrosion (i.e. carbon steel) with a zero corrosion allowance?

 

[gerhardl]

Is the valve taken out of the pipeline for complete service? Only smaller surface improvement work should be done in place.

If not taken out, and in doubt of corrosion damage extent for a 'control valve' of this size (pressure class?) a full demounting and inspection of all parts should be recommended.

For main pressure retaining parts as the body the normal methode is to inspect visually, then 'sandblast' (with most often other more suiteable material than sand), inspect for material faults (visual, radiographic, dye penetrant or combinations), repair if any repairable (if necessary), with procedures (welding procedures for instance), new surface treatment under controlled conditions, re-assemble and test after agreed or given standards. Other parts to be inspected, repaired or replaced before the re-assembly.

If the valve gives a 'normal' performance as it is, cleaning and visual inspection only, without demounting of inner parts could be OK. But what about expected operation time and damages on non-inspected parts then?

 

[Roberto1956]

If this control valve is for flow control, or in other words, it does not close, the sandblast will not affect its thightness, anyway it is important protect inner part. Atfer sandblast you may do a water flow to test or to wash.
About loose thickness, it is possible with a non trainned operator.