derwoodwithasherwood
Contributor
The original post was lost in the great Scubaboard crash of 2007, but I told the tale of the LDS conducting a VIP on my steel tank and "condemning" it on the basis of what they called a "crack" below the threads (picture at http://www.lwra.net/temp/images/crack_2.JPG)
Following the advice I received here, I took the tank to a hydro shop for a second opinion. Basically they laughed. They said that the "crack" is a normal anomaly of the manufacturing process called a "valley" that sometimes happens when the neck is formed. Nothing to worry about as long as the valley doesn't interupt more than x number of threads (6? I think he said).
He went on to say that apparently if this condition occurs in aluminium cylinders made from the "bad" 6351 alloy, it can lead to a crack extending from that fold in the metal. Transport Canada has issued a bulletin about this, instructing hydro facilities to fail all aluminium cylinders (no distinction drawn between 6351 and 6061 alloys) with such deformations at the neck. The edict does not include steel cylinders. His guess is that the LDS mistakenly thought it includes all cylinders.
So: short story is the cylinder is all cleaned up and back in business. And I'll take my business to someone more knowledgeable even though it's a much further drive.
Following the advice I received here, I took the tank to a hydro shop for a second opinion. Basically they laughed. They said that the "crack" is a normal anomaly of the manufacturing process called a "valley" that sometimes happens when the neck is formed. Nothing to worry about as long as the valley doesn't interupt more than x number of threads (6? I think he said).
He went on to say that apparently if this condition occurs in aluminium cylinders made from the "bad" 6351 alloy, it can lead to a crack extending from that fold in the metal. Transport Canada has issued a bulletin about this, instructing hydro facilities to fail all aluminium cylinders (no distinction drawn between 6351 and 6061 alloys) with such deformations at the neck. The edict does not include steel cylinders. His guess is that the LDS mistakenly thought it includes all cylinders.
So: short story is the cylinder is all cleaned up and back in business. And I'll take my business to someone more knowledgeable even though it's a much further drive.
