Doing hydro and visual separately

[Johnoly]

;;;So the first picture - is it before or after the tumbling? If before, do you think it would have failed the visual as shown in the first picture?

Both picture are "Before" tumbling/whipping and cleaning. The 1st picture would surely fail VIP, The 2nd,,,might get past a VIP.
Rust doesn't stop or prevent a Hydro "passing" since you can have double or triple the rust seen here and still pass. The only thing a hydro guy checks is will the tank expand way too much when he over pumps it with pressure to test it (5/3rds usually). He doesn't care if it's shiny, has paint, dings, stickers, anything. All he does is pump it very very over full and check the expansion. Some are so weak, they even explode in his chamber.

 

[The Chairman]

At that point the variance is immaterial.

That is not true. Will over-torquing a tank by %15 or %20 hurt the tank? Probably not. But the angle created by the torque wrench to the crow's foot is immaterial. You will increase the torque by the distance between the center of the drive to the center of the fastener.

 

[Bob DBF]

You will increase the torque by the distance between the center of the drive to the center of the fastener.

Wouldn't it be from the handle pivot to the center of the tank valve? More than with a socket, but less than with the crows foot straight out.

Inquiring minds...


Bob

 

[JackD342]

That is not true. Will over-torquing a tank by %15 or %20 hurt the tank? Probably not. But the angle created by the torque wrench to the crow's foot is immaterial. You will increase the torque by the distance between the center of the drive to the center of the fastener.

Perhaps we are not yet at a meeting of the minds on what we are each saying.

In the following image, I am saying that B is definitely longer than L, and to be exact you should calculate that difference, and use it in place of E in any formula using your crowsfoot at a 90° offset versus your calculation when using it at 0°.

But in actual practice, that relative difference is small enough to ignore. We probably incorporated far more imprecision by deciding that measuring from the center of the handle is "good enough" for our purposes. No way can I say that is exactly and consistently where I apply force when turning my wrench.

Now, if I place a 4" extension on a 9" torque wrench, we have another matter and need to go back to the drawing board. Or if using a fairly large crowsfoot on a fairly short torque wrench, which is pretty unlikely. In my case, my most commonly used cylinder crowsfoot (Sherwood, Thermo, etc.) is 1.5", which adds 2" to the length (E in above diagram) at 0°. If used that way, setting for 35.7 foot-pounds gives me my desired 40 foot-pounds.

Now, using a tape measure rather than spending the next hour or two refreshing my high school geometry (or is it trig?) skills, the same crowsfoot/wrench combination at 90° only adds about 1/8th" to the length rather than 2". That means I set for 39.7 to apply 40. The tools we are using are not that accurate in the first place.

I have visited multiple sites online with conversion formulas, and they all have said to ignore any adjustment for a 90° crowsfoot. Again, an extension is a different matter.

 

[Charles2]

In the following image, I am saying that B is definitely longer than L, and to be exact you should calculate that difference, and use it in place of E in any formula using your crowsfoot at a 90° offset versus your calculation when using it at 0°.
View attachment 487123

At the risk of being pedantic; using the correction for length B is only necessary when the force applied to the handle is perpendicular to line B. If the force applied to the handle is perpendicular to line L, no correction is necessary. The sites you visited that said to ignore any adjustment for a 90° crowsfoot are correct.

 

[JackD342]

At the risk of being pedantic; using the correction for length B is only necessary when the force applied to the handle is perpendicular to line B. If the force applied to the handle is perpendicular to line L, no correction is necessary. The sites you visited that said to ignore any adjustment for a 90° crowsfoot are correct.

Thanks. And they didn't really say to ignore, they just said to use the original torque spec. Although I did find one site for Ford that said to limit that 90° extension to 2". Didn't say why, and didn't give a solution for greater than 2". If that is just a mechanics reference site, it might very well be just avoid bending/snapping the extension.

 

[JackD342]

At the risk of being pedantic; using the correction for length B is only necessary when the force applied to the handle is perpendicular to line B. If the force applied to the handle is perpendicular to line L, no correction is necessary. The sites you visited that said to ignore any adjustment for a 90° crowsfoot are correct.

Hmmm..... now you have me thinking even deeper.

Isn't your point about the different line(s) to which the force is perpendicular applicable only if using a tool that controls and applies the specific force to the handle?

And isn't a torque wrench actually a tool that just provides feedback to tell me how much force I actually applied along the "L" vector, regardless of the angle at which I pushed the handle? If I don't push the handle at 90° to L, I have to apply more force (push harder) the more I deviate from perpendicular, to apply the same torque at the socket pivot.

 

[Charles2]

Isn't your point about the different line(s) to which the force is perpendicular applicable only if using a tool that controls and applies the specific force to the handle?

Not sure I understand your question.

And isn't a torque wrench actually a tool that just provides feedback to tell me how much force I actually applied along the "L" vector, regardless of the angle at which I pushed the handle? If I don't push the handle at 90° to L, I have to apply more force (push harder) the more I deviate from perpendicular, to apply the same torque at the socket pivot.

Generally speaking, Yes. The torque wrench provides feedback to tell you how much torque (not force) is applied at the bit driver (or socket, if it is attached directly to the bit driver) of the wrench. Torque can be thought of as the result of two parallel forces times the perpendicular distance between them.

If you draw a force-moment diagram of your example with the 90° crowsfoot wrench, you will see that if the force is applied perpendicularly to the handle the measurement of the torque will be correct. However, if the force is applied at any angle other than perpendicular, the distance between the forces will vary and the resulting torque will vary as well.

I think you are on the right track. ​

 

[The Chairman]

I see your reasoning... and will agree with it. Thanks for the clarification.