OK, I have a unique application where I need to torque some bolts. We currently torque these with a pneumatic wrench, but we're not confident that the we know what the actual torque value is at the socket and that might be causing us some operational issues.
I have an 8-bolt, circular pattern that I need to torque in succesive cycles of 200, 400, 600, 800 and 900 ft-lbs. We currently attempt to control the torque output of the wrench by varying the air pressure input, but due to unquantified pressure drops in the lines between the air supply and the wrench and degradation of the air pressure/torque curve of the wrench itself due to being operated without lubrication, I am not confident of that we're actually getting.
I should mention that this torquing is accomplished in a very high radiation environment, so no humans can be present to hold the wrench, adjust torques, etc. This radiation environment also precludes the use of any electronics, but electric motors are OK.
I either need to determine a simple way to measure the torque output (a calibration tool) or need to use a wrench that gives me some confidence. I have looked briefly into electric torque wrenches, but they generally need a human to change the torque settings and I'm fresh out of humans. I also designed a calibration tool, but it requires routing transducer cables outside of the work area (difficult) to access the electronic test box (and is expensive), so we haven't pursued it at this point.
Any ideas?
Here's a picture of the current operation:
