August 4 - August 10, 2010
What procedures and tools are needed for assessing the condition of coatings and substrates in a process facility to develop a maintenance painting plan?
Marco Antonio Alvarado Meneses of Consultant Lima - Perú on
August 16, 2010:
Maintenance painting provides an economical means for preventing corrosion and metal loss. SSPC-PA Guide 5, “Guide to Maintenance Painting Programs,” provides procedures for planning and carrying out a comprehensive maintenance painting program.
This guide lists eight potential tasks to identify the key points of maintenance painting activities:
1. Define maintenance painting objectives: Prevent significant loss of metal; continue coating protection of metal; minimize life cycle costs; minimize down time of process units; maintain safety and appearance, etc.
2. Plan and conduct a condition assessment. A survey is necessary. It can be minimal , mid-level, or detailed,depending on the maintenance painting philosophy of the facility.
3. Determine corrective action required. Actions required after the survey can be deferral of painting, spot repair and touch-up only, spot repair follow by full topcoat, or complete removal of the existing coating and replacement of the system.
4. Establish and prepare step-by-step procedures for corrective actions.
5. Prepare the contracts.
6. Secure contracts for labor and materials.
7. Monitor, conduct, and inspect repainting. A quality control plan must be followed.
8. Plan and implement follow-up activities. Conduct periodic inspections in order to ensure good performance of the applied coating. Daily records related to painting inspections must be properly stored by owner.
Stephen Sanczel of consulex on
August 9, 2010:
Some of tools needed in order to assess the condition of existing protective coatings include a camera, DFT gauge, adhesion tester, dull putty knife, pit depth gauge, small can of solvent, and some rags. The process can begin by research to ascertain when the structure was last painted and with what coating material and at what DFT. This information will prove extremely useful in making the final decision on whether a complete coating removal is warranted or will a spot clean and prime and finish extend the life of said coating.
An initial appraisal can be made from a site visit or walk down of the structure in question. During this phase of the inspection, observations can be made of general cleanliness, mechanical damage, extent of corrosion on any pipe brackets, braces, light fixtures, etc. Also, any obvious problem areas should be noted. Problem areas generally consist of areas that may be difficult to coat properly, or areas that are exposed to harsher elements that the rest of the structure may not be exposed to, i.e., higher temperatures, acid solutions,or atmospheric conditions.
Next, the structure should be “mapped” out. This may be done by elevations or sections, depending upon the nature of the structure. That is to say, a boiler in a power plant may or may not be divided the same as a bridge. The idea is to be able to pinpoint the corroded areas and areas that are in good shape when compiling the data collected during the inspection.
Now you are ready to begin the inspection. It always serves you well to take several photos that can be used as an “overview” of the structure and each “area” overview as described above. As you proceed with the inspection, all photos should be documented by photo number if using a digital camera. This insures later on that each photo can be located again in the field for further research and\or repair. DFT readings should be taken in accordance with SSPC-PA 2 to verify the thickness of the existing coating. If there is an area of heavy pitting, readings can be taken with the pit depth gauge to assist in the determination of any steel replacement that may be necessary. Again, all readings should be documented as to the location the readings were taken. Adhesion tests may also be helpful to see if the existing coating is a candidate for overcoating. A solvent wipe can also be performed to help determine the extent of contaminants on the surface and how readily they will clean off. This information helps to make the decision if pressure washing is necessary. Chloride testing can also be a good idea. A dull putty knife is used as described in SSPC SP-3 to determine how well the old coating is still hanging on.
The more data collected in the field, the easier it is to reach the correct conclusion in trying to determine the best course of action concerning the protection of any structure using coatings, that is, to repair the existing coating, overcoat the existing coating or replace the existing coating.
Tom Swan of M-TEST on
August 9, 2010:
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I have attempted to help several plants set up a coating maintenance program and the main problem was commitment by plant management to follow through. Unless you can commit 5 to 10 years to the plan, the payback will be minimal. If you follow through, the savings can be substantial.
When assessing the plant, do not evaluate areas smaller than what you will paint. Doing the survey in too much detail will make your database unmanageable. Make sure areas are clearly identified and can be found by plant personnel.
However you grade the coatings, it will break down to "no work required" (A), "touch up and overcoat" (B), and "total removal and recoat" (C). Put most of your time and money into evaluating the B conditions. Since C conditions will be removed, the only considerations are substrate and temperature.
With B conditions evaluate adhesion, DFT, and the number of coats prior to determining if it can be repaired and over-coated. Your best cost savings is keeping B's from going to C's.
Unless you are trying to preserve the asset, save the C's to last.
The key to the coating maintenance plan working is once you get everything to be in A or B condition, paint it before it gets to be a C. Up front costs can be high. The savings are on the back end of the plan and can be substantial if you stick with it.
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