Previous in Forum: QC Verification   Next in Forum: Searching for Packaging Supply Engineer to Hire
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
24 comments
Rate this Comments: Nested
Massey
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Jun 2014
Posts: 623
Good Answers: 33

SS Bolt Stretch

11/03/2015 1:37 PM

We tightened a bunch of 18-8 SS 1/4-20 HHCS x 1" long with one time use Top-Locknuts a week ago. Upon inspection today, it took another 1/4 turn to torque the same 8 ft*lbs. Has anyone noticed this before? How do you deal with it? Hate to have to torque twice, once for assembly and once again for delivery.

__________________
 Hey Isaac, catch! ...oops, that's gonna leave a mark...
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
4
phoenix911
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 23578
Good Answers: 419
#1

Re: SS bolt stretch.

11/03/2015 1:45 PM

You don't need to torque twice......@ 8 ft*lbs torque, it looks like the bolts were over-tightened. and now they lost their elasticity and are failing.

18-8 SS 1/4-20 bolts should only have been torqued to 75.2 in-lbs dry - 63.9 in in-lbs wet.

or 6.3 ft-lbs /5.3 ft-lbs respectively.

__________________
 “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply Good Answer (Score 4)
Go to Next Good Answer
phoenix911
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 23578
Good Answers: 419
#2
In reply to #1

Re: SS bolt stretch.

11/03/2015 2:02 PM

One other thing,.... were these bolts 'used'? or already have been in service.

__________________
 “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply
SolarEagle
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33315
Good Answers: 1810
#4
In reply to #1

Re: SS bolt stretch.

11/03/2015 3:53 PM

Phoenix911 appears to be correct...

https://www.fastenal.com/content/feds/pdf/Torque%20of%20Stainless%20Steel,%20Non%20ferrous%20Torque.pdf

__________________
 All living things seek to control their own destiny....this is the purpose of life
Register to Reply
SHOCKHISCAN
Guru

Join Date: Nov 2007
Location: Eastern Arizona mountains on Route 666 about a mile from God's country
Posts: 1676
Good Answers: 122
#3

Re: SS bolt stretch.

11/03/2015 2:10 PM

What is the manufacturer country of origin?

We have experienced severe issues with bolt quality that does not meet standards resulting in bolt stretch and loosening before any load is applied to them.

We are suffering a high incidence of in-service new bolt failure also.

Replacing the poor quality bolts with high quality bolts manufactured in reliable countries has solved the issues.

We have had to place several items such as bolts, valves, and lifting devices in our warehouse Global Sourcing "purchase not allowed" category.

Choosing lower price over quality never works out for the best.

__________________
 They said; "Brain size?" I heard; "Train size?" so I said: "I'll take a small one, thank you."
Register to Reply
aurizon
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3968
Good Answers: 120
#6
In reply to #3

Re: SS bolt stretch.

11/03/2015 5:11 PM

Yes, In China, their production practices are so advanced that scrap steel melted bots can be turned in Stainless Steel with a rubber stamp on the box that says "Stainless Steel"

It is a wonderful way to save money.

__________________
 Per Ardua Ad Astra
Register to Reply Score 1 for Good Answer
No more "Almost" Good Answers.
texasron
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Oct 2013
Location: Texas.Baytown
Posts: 697
Good Answers: 26
#12
In reply to #6

Re: SS bolt stretch.

11/04/2015 7:31 AM

Several years ago there was a drug dealer that got out of the drug business to make grade 8 bolts. All he did was to imprint Gr. 8 on the head.

__________________
 If you want to know how well a broom works you do not ask the guy selling the broom or the guy who designed the broom, you ask the guy using the broom.
Register to Reply
lyn
Guru

Join Date: Oct 2008
Posts: 42376
Good Answers: 1692
#5

Re: SS Bolt Stretch

11/03/2015 5:06 PM

OOPS! This could kill a lot of Atta-Boys.

Register to Reply
SHOCKHISCAN
Guru

Join Date: Nov 2007
Location: Eastern Arizona mountains on Route 666 about a mile from God's country
Posts: 1676
Good Answers: 122
#7
In reply to #5

Re: SS Bolt Stretch

11/03/2015 5:18 PM

Yep. I don't know about anyone else but in my world 1 Oh-Sh*! cancels 200,000 "Atta-Boys"

__________________
 They said; "Brain size?" I heard; "Train size?" so I said: "I'll take a small one, thank you."
Register to Reply Off Topic (Score 5)
lyn
Guru

Join Date: Oct 2008
Posts: 42376
Good Answers: 1692
#8
In reply to #7

Re: SS Bolt Stretch

11/03/2015 11:00 PM
Register to Reply
old salt
Guru
Safety - Hazmat - New Member Engineering Fields - Retired Engineers / Mentors - New Member Engineering Fields - Piping Design Engineering - New Member Hobbies - DIY Welding - New Member Fans of Old Computers - PDP 11 - New Member

Join Date: Feb 2007
Location: Stronger Than The Storm
Posts: 2394
Good Answers: 203
#9
In reply to #7

Re: SS Bolt Stretch

11/04/2015 12:04 AM

I like my world better. It's always been 50 got wiped out.

Good Luck, Old Salt

__________________
 Any day on the green side of the grass is a GREAT DAY!, --- me +++++++++. I believe creativity is an inherent part of everyone. --- Kermit T. Frog
Register to Reply
adreasler
Guru
Engineering Fields - Electrical Engineering - New Member Fans of Old Computers - Commodore 64 - New Member Popular Science - Evolution - New Member United States - Member - New Member

Join Date: Oct 2013
Location: Illinois, 7 county region (The 'blue dot' that drags the rest of the 'red state' around during presidential elections.)
Posts: 3688
Good Answers: 89
#17
In reply to #7

Re: SS Bolt Stretch

11/04/2015 9:18 AM

Yup, just take a look at the paperwork for your Employee Review the next time you ask for a raise:

You could have saved the company several hundred thousands of dollars, improved the company's output 300%, AND saved the CEO's life TWICE during the past year, but "This pattern of you clocking in late every Thursday for a month" (Which was your supervisor stopping you before you got to the time clock to try and get you to buy the horrid candy for his little girl's school fundraiser, incidents that were clearly caught on the company security cameras, you would have been at the time clock on time, a few minutes ahead of your shift in fact, but your supervisor's antics were causing you to clock in two minutes past the start time) means you're not eligible for a raise this year, you really need to learn to be a 'team player.'

Yeah, that's an extreme example, but it seems that no mater what miracles you pull off, your boss seems to find ways to negate them with something trivial.

__________________
 ( The opinions espressed in this post may not reflect the true opinions of the poster, and may not reflect commonly accepted versions of reality. ) (If you are wondering: yes, I DO hope to live to be as old as my jokes.)
Register to Reply Off Topic (Score 5)
phoenix911
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 23578
Good Answers: 419
#19
In reply to #17

Re: SS Bolt Stretch

11/04/2015 9:37 AM

I was the engineering manager at a company in the 90's and the owner and president of the company always sat (stood) by the exit door after you clocked out to talk to you on the current or new projects or issues. Always at the minimum of 1/2 hour usually 45 minutes to and hour long.

It became a joke and quite comical. So I told the engineering group lets make it difficult for him and see what kind of reaction we get by all (and these were my exact words) Herd up in engineering and make a quick dash to the door like a herd of water buffalo crossing a crocodile infested river.

There was so much laughing going on as we charged to the gates especially the look on the bosses face of 'wtf,..... I wanted to talk to these guys'.

A lot of the guys just lost it. It was a National Geographic moment.

__________________
 “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply Off Topic (Score 5)
Massey
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Jun 2014
Posts: 623
Good Answers: 33
#10

Re: SS Bolt Stretch

11/04/2015 7:09 AM

These appear high end brand new one time use bolts with top-lock nuts. The customer spec is 8-10 ft*lbs. So I had them torque to 8. Since I also believe the spec is too high. Looks like I am going to try to convince a large international company to review/revise their specs. I said 18-8 but these are 316.

__________________
 Hey Isaac, catch! ...oops, that's gonna leave a mark...
Register to Reply
2
phoenix911
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 23578
Good Answers: 419
#11
In reply to #10

Re: SS Bolt Stretch

11/04/2015 7:15 AM

The customer specification is incorrect.

The problem is on their end..... did they get confused with coarse thread (1/4-24) and fine thread (1/4-20) specifications?

I believe that's where the problems lies.

__________________
 “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply Good Answer (Score 2)
Go to Next Good Answer
jhowdy
Guru

Join Date: May 2011
Location: Northern California
Posts: 803
Good Answers: 81
#21
In reply to #11

Re: SS Bolt Stretch

11/04/2015 1:37 PM

Looks like you mixed up your fine thread with your coarse. 1/4-24 is finer than 1/4-20.

__________________
 "Why do things that only happen to stupid people keep happening to me?" Homer Simpson
Register to Reply
phoenix911
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 23578
Good Answers: 419
#23
In reply to #21

Re: SS Bolt Stretch

11/04/2015 2:04 PM

good catch... .. and let that be yet another lesson on how easy it is for an error to happen.

__________________
 “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply
Hilton
Guru

Join Date: Jun 2011
Location: Mossel Bay, SA
Posts: 777
Good Answers: 21
#24
In reply to #10

Re: SS Bolt Stretch

11/11/2015 5:45 AM

My first thought actually...316 is no good for any application requiring a torque setting in my experience, simply too soft.
Register to Reply
roy hammy
Guru

Join Date: Jun 2009
Location: Ontario Canada
Posts: 930
Good Answers: 31
#13

Re: SS Bolt Stretch

11/04/2015 7:52 AM

Always get a mechanical certificate on hardware purchases and if from a suspicious source have another test done on home soil. This advice comes from numerous bad experience which was solved with the certificate of compliance. My designer draftsman handled this issue as part of his contract.

__________________
 The fine line between cuddling and holding one down to prevent escape must be learned
Register to Reply
Massey
Guru
Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Jun 2014
Posts: 623
Good Answers: 33
#14

Re: SS Bolt Stretch

11/04/2015 8:03 AM

Thanks all. This was customer supplied hardware and torque specs.

__________________
 Hey Isaac, catch! ...oops, that's gonna leave a mark...
Register to Reply
adreasler
Guru
Engineering Fields - Electrical Engineering - New Member Fans of Old Computers - Commodore 64 - New Member Popular Science - Evolution - New Member United States - Member - New Member

Join Date: Oct 2013
Location: Illinois, 7 county region (The 'blue dot' that drags the rest of the 'red state' around during presidential elections.)
Posts: 3688
Good Answers: 89
#18
In reply to #14

Re: SS Bolt Stretch

11/04/2015 9:29 AM

"Here are some bolts, torque them to 8-10 foot-pounds."

"Um, the bolts you supplied aren't rated for that level of torque."

"Nonsense, take the bolts I gave you and torque them like I said."

(Some customers just don't understand that you can't get Red Roses from a White Rose Bush.)

__________________
 ( The opinions espressed in this post may not reflect the true opinions of the poster, and may not reflect commonly accepted versions of reality. ) (If you are wondering: yes, I DO hope to live to be as old as my jokes.)
Register to Reply Off Topic (Score 5)
Petor2
Associate

Join Date: Dec 2014
Posts: 33
Good Answers: 2
#15

Re: SS Bolt Stretch

11/04/2015 9:07 AM

I was taught to loosen the nut slightly before re-torquing. If you mark the nut and bolt before loosening and then re-torquing, it would be interesting to hear the result.
Register to Reply
phoenix911
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 23578
Good Answers: 419
#16
In reply to #15

Re: SS Bolt Stretch

11/04/2015 9:12 AM

That sounds similar to preloading.

Preload is the term used for a bolt's clamp force.

__________________
 “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply
bullardrr
Power-User

Join Date: Mar 2014
Posts: 373
Good Answers: 2
#20

Re: SS Bolt Stretch

11/04/2015 10:01 AM

Without looking at all comments, the two issues are likely micro-galling (esp. with locknuts) and temperature rise (esp. at rapid torquing). With the former, try going to full torque, then backing off slightly and re-torquing to spec.
Register to Reply
2
jhowdy
Guru

Join Date: May 2011
Location: Northern California
Posts: 803
Good Answers: 81
#22

Re: SS Bolt Stretch

11/04/2015 1:50 PM

I would think that just turning a locknut (with it's higher amount of friction) would "use up" a portion of the torque applied.

It may take a few pounds just to move it on the threads before clamping force is even a factor.

Add this additional friction to the torque required for the clamping force (or bolt stretch) and it may explain their higher torque requirement.

If you torque charts took that into account already, then nevermind.

__________________
 "Why do things that only happen to stupid people keep happening to me?" Homer Simpson
Register to Reply Good Answer (Score 2)
No more Good Answers. Go to first "Almost" Good Answer
Register to Reply 24 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

adreasler (2); aurizon (1); bullardrr (1); Hilton (1); jhowdy (2); lyn (2); Massey (2); old salt (1); Petor2 (1); phoenix911 (6); roy hammy (1); SHOCKHISCAN (2); SolarEagle (1); texasron (1)

Previous in Forum: QC Verification   Next in Forum: Searching for Packaging Supply Engineer to Hire

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Quality Assurance / Control:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (66 right now)
Show Members
Advertisement