In Reply to: Re: Best of 2019 posted by Halibug on December 25, 2019 at 22:08:52:

Here's a post about the construction of one of the early pipes that I came across on Scubaboard. Hairy stuff!

Excerpted from The History of Oilfield Diving: An Industrial Adventure
by Christopher Swann (Oceanaut Press)​

In the summer of 1957, Associated Divers, at the time the dominant diving company in California, were contracted to provide standby divers for a job in 312'/95M of water. S.V. "Sammy" Collins, of Collins Construction Company in Port Lavaca, Texas, who was involved in the pipeline business in the Gulf of Mexico, had just finished pulling a 20"/51CM sludge line out into the ocean from the Hyperion sewage plant in El Segundo. The line ended at the edge of the Santa Monica submarine canyon, into whose depths the ground-up waste that the sewage plant was incapable of handling was to flow.

Because it had a thick cement coating on the outside and a mortar coating on the inside, to protect it from the effects of the effluent, the pipe was extremely heavy. Collins had therefore capped it to keep it full of air, to lighten it and to prevent the sled on which the end was resting from plowing into the bottom as he dragged it offshore. Once the line was in place, the pressure in the pipe would be raised to shear the specially machined retaining bolt and blow out the plug, and the plant would start pumping.

Collins was in a tight spot, however. The engineers for the City of Los Angeles would not accept the line until he had run a pressure test to prove its integrity, and he suspected that the end plug—shaped like a cone, with the narrow end facing out—was leaking..

Collins had brought with him from Texas a young Gulf Coast diver, Ray Savard. Savard was to go down and tighten the bolt that held the plug, to try to get it to seal; otherwise Collins was going to lose a great deal of money. The standby divers were first, Murray Black and second, Charlie Isbell, who was by then 47 years old. Isbell was not at all confident that Savard was capable of making the dive; even at Associated, nobody had worked deeper than 280'/63M. But as Black said: "What was Ray going to do? He couldn’t back out; we were all looking down his throat, wondering what he was going to do."

On the bottom, rigged so that it was looking at the end of the pipe, was a television camera, with a powerful set of lights. As soon as Savard left the surface, Isbell went into the TV tent to watch the dive on the monitor. At about 260'/79M, word came from Savard that the lights had blown out. Isbell, who could see perfectly well that the lights were still on, realized with increasing trepidation that it was not the lights that were malfunctioning but Savard’s optic nerve, which was sending scrambled messages to his brain.

On the bottom at 312'/95M things naturally got worse. Savard made no attempt to tighten the bolt; the only thing he did was pick up a handful of gravel, which he put in the pocket of his chafing pants, to prove to a deckhand that he had reached the bottom. Then he started wandering back and forth between the sled and the television camera, the knee patches on the dress of his Mark V heavy gear standing out sharply in the clear water.

"The lights have gone out!" He kept saying. "I can’t find the TV camera".

At that point, Isbell decided the dive had gone on long enough. Although Savard had been on the bottom no more than eight minutes, Isbell yelled to the tender to pull him up.

Isbell was worried that Savard, already rendered useless by nitrogen narcosis, might be hit at any moment with oxygen poisoning. This is a serious danger breathing air at 312'/95M where the partial pressure of oxygen is just over 2.0 atmospheres, a level considered barely tolerable for the briefest of exposures, and then only if the diver is at rest.

Savard was definitely not at rest. He was walking about, building up carbon dioxide in his helmet, and Isbell knew all too well that carbon dioxide retention was as much a factor in oxygen poisoning as it was in nitrogen narcosis. There was every possibility that Savard would suddenly go into an oxygen convulsion, similar to an epileptic seizure. Furthermore, Isbell was concerned Savard might go under the end of the pipe, which was well above the bottom on the sled, fail to retrace his steps to clear his hose, then inflate his dress to come up; in which case he would probably blow up upside down, anchored to the pipe by the bight of his hose.

Whether Savard passed out on the bottom, as Black remembered, or whether he simply did not understand his tender when he told him to start his ascent, is not certain. In any event, the tender had to pull Savard up off the bottom. Since he evidently had his air valve wide open, he shot straight to the surface, fortunately clear of the barge. By some miracle he survived, to emerge from the chamber with nothing worse than a slight twinge in one elbow—only to die ten years later cutting foundation piles for the Narragansett Bridge on the East Coast.

Three or four days after Savard’s hair-raising experience, at Collins’s request Isbell and Black returned to do the job. It was decided that Black, being younger and stronger, would make the dive, with Isbell standing by. As with Savard, Isbell was concerned that Black should not go under the pipe.

"In 300 feet of water I could go down and maybe get him out, but maybe I couldn’t. If he had blown up with too much air there would be no way I could haul him down. I would have had to get up off the bottom and turn his air down and bleed enough out—which might be too much; and, in the meantime, he would be in an oxygen convulsion and maybe die."

The minute Black reached bottom, he went to work on the retaining bolt, holding onto the hinge hook which held the top of the cap in place with one hand, and pulling on the wrench with the other. He then told Isbell he was going to cross under the pipe to get a better purchase on the wrench.

"Don’t go under the pipe!" Isbell barked into the telephone. "I told you not to!"

But it was too late. Black was already putting a dying strain on the bolt, and by now the combined effects of nitrogen and carbon dioxide were starting to catch up. He knew that in another 30 seconds—45 seconds at most—he was going to lose consciousness. He pushed himself out from under the sled to clear his hose, and passed out. He had been on the bottom for eight and a half minutes. When Black came to, he was at 280'/85M. The rest of the ascent went off without incident.

Later that day the pipe passed the pressure test.​

• Zow! (-) seahunt 02:14:26 12/30/19 (0)
• Re: Speaking of the Sh*tpipe Halibug 22:28:12 12/27/19 (0)