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Mechanical Engineering


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  1. Hello everyone, I'm not entirely sure if this is the right place to ask this question, but I'm not sure where else it would go. I've heard from someone who used to work in the industry that oil and gas companies have seamless pipe expanders, with smooth and flexible exteriors, that go inside a pipe, then increase their OD using hydraulic pressure to expand the pipe. So, like an inflatable pipe plug, but strong enough to actually yield the metal. He described it as looking like an air suspension bag for a car. (NOT like a hydraulic pipe expander that simply uses a hydraulic ram to force a tool into a pipe, enlarging it as it does.) I can't seem to find this anywhere. Does it not exist, or is my Google-fu just weak? Thanks, Alex
  2. Hello everyone, I'm new to the forum, trying to solve an engineering problem. I have ideas, but wanted to brainstorm here and see if anyone else may have a better one. I have a steel cylinder (roughly 3.6 inches diameter, 6 inches long) with a hole through its center. A shaft is pressed into that hole with an interference fit. I want to put a torque wrench on the shaft to test how much torque it can withstand without slipping. To do this I think I will need to hold the cylinder still, and I am brainstorming ways to do this. I need to test it up to 50 ft*lbs, and would like to have the ability to go up to 165 ft*lbs. I am considering a strap wrench, as they're available in rubber (high friction) and they self-tighten as more torque is applied. However, I'm not sure if a strap wrench would be able to handle that without slipping. I do not want to cut into or damage the cylinder. It's quite strong and can resist a lot of crush force, but teeth biting into it are likely to cause damage. Any input is appreciated!
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