Blast and Paint
Shot blasting, sand blasting, and painting flanged spools and valves places the critical flange sealing surface at risk if not properly covered. Traditionally, tape masking is used to cover the critical flange face sealing surface during the blast process. Tape masking is extremely time consuming and leaves the potential for portions of the flange face to not be properly covered. Additionally, not properly covering the flange opening when blasting/painting valves, can allow blast media to find its way into your valve causing cleanliness issues and potential valve damage.
Masking Tape: Taking rectangular tape and making circles is time consuming and can cause damage and hand injuries. Box cutters are generally used to trim making tape. During the process of trimming tape, fingers, hands, and the gramophone can come in contact with the blade. Accidentally cutting across the sealing surface of a flange or valve can cause enough damage to fail both B16.5/B16.47 and PCC1 inspections. Lacerations caused by box cutters that require stiches or a tetanus shot is considered an OSHA recordable.
Adhesive Issues: The adhesive in masking tapes contains chlorides. Using masking tape on stainless steel flanges and valves is a big No No! Masking tape adhesive (especially in hot environments) tends to be left behind upon tape removal.
Thickness: When using masking tape for blast/paint, double masking is necessary. If primer/paint bleed through masking tape and find its way on the flange faces, cleaning is required. B16.5/B16.47 and PCC1 do not allow primer/paint to be left on flange faces (sealing issues).
Cleanliness: Blast Media and dust that enters the bore of a flange can cause cleanliness issues and damage. Blast media can cause damage to valve seats, which in turn, can cause the valve to leak. Valves used in food grade applications cannot have ANY internal foreign material as process solutions can be contaminated. Additional tape making is required for the exposed valve stem and tubing openings (actuated valves). Accidentally blasting/painting a valve stem or getting blast media inside tubing connections can cause valve damage. Blasting and painting of flanges and valves is now complete. Tape is required to be removed. How will you ensure cleanliness is maintained?
Risk: Each time tape is cut for masking is a potential risk for injury. Are you using self-retractable box cutters for tape masking? Hand injuries are the number one cause of recordable injuries in the workplace. How many pieces of masking tape are cut daily for blast and paint masking? The bigger the flange size, the more masking tape is required to be used, the bigger the risk.
Time: How long does it take to mask a flange or valve? Remember, we discussed two layers of tape is required to prevent paint/primer bleed through. Masking tape at face value may seem inexpensive to use, however, include your labor costs in the calculation… I think you will be surprised at the overall cost.
COST: Material costs fortwo layers of tape per flange opening. Additional material costs for masking tape for valve stems, actuators, and tubing connections. Labor cost for masking tape application. Labor costs for making tape removal. Material costs for flange, valve preservation upon completion of blast/paint. Labor costs for application of flange and valve preservation. Material and labor costs associated with re-working valves due blast/overspray/cleanliness issues. Labor costs associated with lost time injuries incurred while using a box cutter.