Testing: Installing test blinds, dropping controls valves, equipment isolation, drying and re-instatement after testing is a risk to previously installed piping, valves. Instrumentation, equipment, etc. Damaged flanges, leaving pipe open, and not protecting items dropped for testing purposes can cause re-work and project schedule delays.
Borescoping: Spools leading to the suction side of compressors, lines that are associated with stringent cleanliness requirements, instrument air lines, etc. are often required to be borescoped to ensure materials and debris are not present. Borescope before pneumatic testing and remove material and debris before performing pneumatic testing. In extreme cases where material and debris are difficult to remove, lines may need to be cut for material and debris removal!! Debris and material removal can be completed post hydrostatic testing if removal does not necessitate line cutting. Borescoping post hydrostatic testing/drying can also confirm the line has been adequately dried. Protection of openings is crucial during borescoping. If borescoping a line shows the line to be clean and dry, not closing/protecting openings post borescope can render a once clean line in need of rectification. If borescoping shows a line in need of jetting/back blowing, closing open connections post cleaning is critical to avoid re-work.
Blind Installation: Installing testing blinds is necessary to isolate only the line being tested. Blinds also isolate equipment and components from test pressures. Care must be exercised when installing blinds to ensure critical sealing surfaces are not damaged during installation. Spacer ring vs blind position must be checked at equipment locations to ensure water does not enter critical equipment.
Dropped Valves/PRV’s, Etc.: Control valves and pressure relief valves are installed to check if they fit but cannot undergo testing and must be removed from the testing process. Valves and PRV’s need to be re-preserved once dropped from testing. Dirt, debris, rain, etc. can quickly damage expensive/critical equipment if not protected. PRV’s may not be re-installed until commissioning due to calibration requirement and should be re-preserved and sent upright back to the warehouse or other temporary storage location.
Drying(Hydrostatic Testing): Drying test packages completely can be difficult due to line configuration. Removing as much water as possible BEFORE beginning the drying process is critical. Hitting a specific dew point is often used to determine line dryness. Dew Points much be checked a multiple locations(especially the lowest point farthest away from the compressor) to determine dryness. Drying with nitrogen is effective, but often poses safety risks. Borescoping to confirm dryness is preferable if access and line configuration allows. Once the line is determined to be dry, every effort should be made to ensure the line stays dry and closed.
Reinstatement: Testing is complete and blind removal has taken place. Lines are open, equipment may open, valves need to be re-installed. One of the most overlooked part of preservation/cleanliness in lagging restoration. Temporary protection to ensure lines, equipment, valves, etc. stay clean, dry, and closed is a must, yet often overlooked activity.