Arc Welding 101: Tackling trailer troubles

Q: A routine preventive maintenance inspection on a steel flatbed trailer revealed cracking in the main frame beams. The trailer was purchased through a distributor, so it was returned the next day. We asked the manufacturer to send a qualified representative to inspect it and send us a proposal for a remedy. The manufacturer refused but instructed the distributor’s mechanic to patch it up as best he could. Is there another alternative?

A: Yours is an interesting problem. After reading your e-mail, I made several attempts to contact the trailer manufacturer but was unsuccessful.

My advice to you is first to identify the extend of cracking. Your local weld supplier should be able to provide you with a dye-penetrant test kit (PT). Remove all foreign material around the cracked area (go beyond the crack), and per the provided instructions, you should be able to see the total length of cracking at the surface. Once the PT exposes the crack, photograph it to ensure that the location and extent of cracking are clear.

Carefully place a clear cellophane tape over the penetrant indications. When you remove the tape, you’ll have an excellent record of what the penetrant testing revealed. Stick that tape on a clean piece of black paper and hang on to it, as this is a great record.

Next, contact the trailer manufacturer directly. Explain your situation and share the pictures and dye-penetrant results. This will give them a better opportunity to evaluate the problem. If they suggest a repair, make sure they provide a written WPS for it. If your trailer is repaired, ensure those completing the repair are qualified per the trailer manufacturer and they strictly follow the WPS.

Weld and base metal cracks can be a “fickle mistress.” They are more commonly due to the design failing to meet the as-used conditions. You know the as-used conditions, and they know the intended conditions. This situation will require both of you to work through this so they can better understand how these cracks developed, how they are best repaired, and how to avoid them in the future.