Using match marking techniques to verify correct linkage settings is an important visual verification pre-start-up technique that can save lives. Consider this and other pre-start walk down issues such as verifying open purge fan intakes, making sure that automatic valves are closed, and reviewing air switch tubing connections in a customized pre-start safety checklist.
Linkages that have changed position could make for improper fuel-air ratio adjustments. If this happens on the lean side, it usually means you will not light off properly. If it happens on the rich side, it could make for a flame out and/or low oxygen fuel-rich conditions. Fuel-rich conditions allow for carbon accumulations and enhance the chances for equipment fires and explosions.
When things change it is often very difficult and sometimes impossible to know until it is too late. The difference between safe and unsafe can be thousandths of an inch when it comes to linkages. Properly positioned linkages rely on repeatable performance over thousands of cycles and years of service. Linkages also rely on screws, shafts, slots, and mechanical force applied to relatively small diameter metal rods to be precise year in and year out.
So What Is Match Marking And How Do I Do It?
Match marking is the process of marking the correct position of each shaft and of linkage connections with respect to each other. This can be done with a permanent marker or through the use of spray-painting techniques. A couple of different examples are provided below.
All techniques will deliver the same result: quick visual notification that something has changed and increased safety from the early notification of a hazard. Simple tactics with the increased practice of pre-start walk-arounds are no cost ways to ensure equipment is operating as intended, and that those working with and around the equipment are kept safe.
Honeywell Combustion Safety, formerly CEC Combustion Safety, LLC, has been in business since 1984. With engineers and staff members that sit on Code committees such as ASME CSD-1, NFPA 56, NFPA 85, NFPA 86, and NFPA 87, our inside expertise is integrated within all of our practices and our global reach ensures that customers around the world are kept safe. Contact us at +1 216.749.2992 or visit www.combustionsafety.com for additional information.