Hopefully I posted in the best place, pressure systems have not really been my area of focus but I do have a need for reworking one currently.
We have an older drawing calling out a 1/4" OD, .035" wall tube that is flared (via SAE AS4330) and connects via sleeve and coupling nut to an AN-type...
Hi again,
We had been using MIL-PRF-46010 heat-cured DFL on the fasteners before. I think much of the problem being the lack of "clean threads", since that was almost certainly not the case previously. We are calling out the torque on the installation drawings, in addition to cleanliness...
Missed rb1957's last response. I apologize for the confusion, the question/problem did shift somewhat after the first post. Initially the problem was merely trying to understand the "fatigue load" columns in the NAS spec, the issue morphed into determining where to find reference-able material...
We would use the material yield data only for preload/strength ratio estimations.
It seems some confusion was created in that a material min yield value is normally provided for many commercial fasteners (ex. Grade 8), and that is not always the case for NAS fastener/materials, which defeats the...
Hey,
Thanks for answers so far. Sorry for the delay in response.
I think the comments are spot on, it's more of procurement/test value and it would be ill conceived to try to use these as a design value or something. The "low" number was throwing me, as mentioned, as any strength/preload value...
Hello,
We are comparing several NAS bolt options as a replacement for an existing joint on a fairly short schedule and am looking into one we haven't used before. I noticed that on the NAS624-644 bolt spec sheet data table there is a header "fatigue load lbs +/-2%" with "high" and "low" columns...
Thanks for responses everyone! Wanted to follow up with some results from this during the initial test operations.
We are using the 6-pt on the open side we are torquing from, but we did have to use a 12-pt on the nut due to requiring a smaller tool/socket there (space restricted side).
We were...
Thanks again for all the answers! We got tied up with a lot and I got pulled onto a different project and this fell to another engineer to try to figure out. It was more of the ordering issue at this point, we determined that we could get acceptable bolt/material certs from several vendors (just...
That's a great point! I forget about that reality sometimes because we are typically asked to "ignore the effects of friction" for reasons of conservatism in analysis. It's probably actually pretty complex to try to estimate that torque relationship with the backing tool.
We have a through-bolt joint where there is very limited access to one side of the interface. We are planning to torque from the open side using either a torque multiplier or a calibrated electronic impact driver. The other side (restricted area) is a 12-pt nut with 1.5" flat-to-flat, and the...
Appreciate the responses! I got tied up and just getting back to the issue. I think we definitely have a path forward now and better understanding. If there are any issues with our planning to call out a specific vendor/bolt on the drawing (essentially a vendor's SKU number), we will likely use...
It's money and availability on the fasteners we are worried about. We have large safety factors and a very conservative, simplified analysis approach (analysis doesn't have time to sharpen the pencils due to a short schedule), so I have to keep around 150ksi ultimate to make the bolt calcs...
I appreciate the responses so far. I have run across Portland bolt in the past, but now looking their site is again very useful. I might have them write up a quote and see what they can do in terms of the certs.
I hadn't checked into A-193 bolts, but they do look to have a shade less tensile...
In our work we usually (pretty much always) deal with NAS fasteners and so we are use to having a very specific fastener code to place on drawing EPLs to allow the shop to order the exact fastener we need from any number of industry vendors. We are now designing a piece of tooling and are...
Right, you hit on more or less my exact concerns. The gut feel of the lifting crew is regards to "standard" day to day lifts that are made without engineering consult. I.e. the shop guys just grab a crane and reposition a 500lb machine or something across the floor. When they are using...
Thanks for the answers and the links to the standards and lifting beam design. I had actually browsed though the BTH 2014 standard, and they appear to have removed all the helpful diagrams and changed the methodology for determining lug/shear plate calculations. The documents shown here are much...
We have a lot of old lifting equipment around and are having compatibility issues with trying to design new hardware for them. In particular, many of our bridge cranes have load blocks with pins to attach lifting devices. Frustratingly, these pin sizes vary between the cranes and many of them...
I’ve been there with issues where we just could not get fasteners to stay tight. Honestly, I’d suggest moving away from torque based locking methods and find a mechanical solution (“positive locking”). The match drilled pin or castle nut are example of this. Lockwire is another, it is slightly...
Thanks for the responses! It’s a martensitic stainless. Their certs seem to indicate they followed the correct conditioning procedure, but I don’t see data on the times/temps they used. Heat treat was per ASTM 564/564M, and that spec doesn’t look as well defined as the ones mentioned. It says...
We purchased a run of specialized stainless forgings and the product the vendor delivered is testing about 30% higher than the yield and ultimate properties we requested in the spec. While the additional strength itself is not problematic, it is causing concern among our team because it's above...
