Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / Technical Discussions / Repair crack on 300bar Hydraulic Cylinde
- - By kk_chiong (*) Date 04-11-2003 13:18
Anyone who has experience on repair a 300 bar hydraulic cylinder in hot press for a chipboard company. We have try to use electrode of AWS E312 (Multi purpose) electrode but it does not last long. Crack develop again after 3 weeks. The base materials for this hydraulic cylinder is cast steel but not sure from what grade (Manufacturer refuse to provide further information). Diameter of the Cylinder is approximately 400mm with the wall thickness of about 70mm. Crack line is same direction as the direction of the the piston travel. If anyone who has experience in this type of repair, please share with me. Thanks.
Parent - - By Michael Sherman (***) Date 04-12-2003 18:40
You need to achieve full penetration over 100% of the crack to assure it will not propagate. Failing this you may be able to drill a small hole in each end of the crack to stop it. Then proceed with your weld. You probably have hydrogen in the weld from the oil contamination, this isn't helping the quality of your weld. A good preheat, an E6010 root to help deal with the contamination followed by low hydrogen electrodes may help.

Mike Sherman
Shermans Welding
Parent - - By kk_chiong (*) Date 04-13-2003 12:48
Dear Michael,
We have try to repair this with the Esab OK55.00 (AWS E 7018 low hydrogen electrode) but the repair can only last for above 1 week and the weldment crack after that. The preparation work is carried out by preparing V groove and left above 5mm before touching the inner surface of the cylinder. Is there any other suggestion that we can try, please advice.
Thanks & Regards, KK Chiong
Parent - - By Niekie3 (***) Date 04-16-2003 19:22
Hi KK

If the cracking is not taking place within 72 hours following the welding, then the problem is probably not caused by hydrogen contamination. Let us know if there is any cracking detected within 72 hours of the welding being completed.

If I understand you correctly, the crack is propagating in the longitudinal direction on the cylinder. This would be typical of a failure caused by the internal pressure. If the original failure was caused by fatigue due to internal pressure, then the cylinder would now be past it's fatigue life. If this is the case, then repairs can only be seen as "temporary", because fatigue will again be initiated extremely rapidly.

Can you tell us:

1) How long this cylinder was in service before it failed the first time. (Possibly the approximate number of stress cycles.)
2) Does it crack within 72 hours of being welded.
3) Do you perform radiography on the weld.
4) What is the hardness of the cylinder material.
5) What is the hardness of the weld metal and HAZ following welding.
6) Is the subsequent failures in the weld, or HAZ of the repaired weld, or somewhere entirely different.

Regards
Niekie Jooste
Parent - - By kk_chiong (*) Date 04-18-2003 17:00
Hai Niekie3,

Thanks for your advice and I like to reply your question as follows;-
1.At least 5 years. The crack first started about 6 months ago and the usage of various electrode give various life span before crack again.
2.It doesn't crack within 72 hours (Visual inspection only). Th ecrack start between 7 days to 30 days depending on the welding materials used.
3. We did not performance radiography test on the weld.
4. Not sure but the materials can be file by hand.
5. Not sure.
6. The failure is more on HAZ.

Hope that you can provide further info.

Regards,

KK Chiong
Parent - - By Niekie3 (***) Date 04-19-2003 10:04
Hi KK

The only questions you did not answer, concerned the crack direction and the hardness of the material before and after welding. I will assume that the crack direction is longitudinal and that you do not have excessive hardening in the HAZ. You will have to tell me if these assumptions are not valid.

From your description, I believe that you have now come to the end of the fatigue life of your cylinder. In the case of components such as hydraulic cylinders, there are few if any obvious stress raisers. For this reason, the initiation of fatigue damage will take a long time, but will be quite incipient in that it will take place all over the component. The damage will not be limited to the area of initial failure. What this means is that when you repair the cylinder by welding, the high residual stresses introduced will acelerate the crack propogation in the HAZ of the repaired material.

I am not sure how large the cylinder is, but if possible, it may be instructive to perform a DPI or MPI on the inside surface before you perform the repairs. It may be possible that you have some vissible defects on the inside surface of the cylinder. Defects that have not yet propogated to the outside. Even on a small cylinder, it may be possible to perform a DPI using something like a water washable penetrant.

The bottom line? At this stage I believe you will be much better off replacing the cylinder rather than repairing it.

Regards
Niekie Jooste
Parent - - By kk_chiong (*) Date 04-20-2003 14:15
Niekie3,

Your assumption on the crack line and the hardness concern is correct and may be your info regarding the cylinder life span is almost there and not much can be done for repairing them with welding. Currently, the cylinder has been order and is awaiting for arrival. Thanks for your advice. And I will have another type of cylinder having same problem but the crack line is on different direction (Surronding the cylinder perimeter at one end of the cylinder). Various electrode has been used arange from AWS E6013, AWS E 7018, AWS E 312 etc... Our current solution to repair them by AWS E6013 since the repair is almost having the same life span. Photo available if you are interested to view them. Please provide e-mail address in order I can forward them to you.

Bye.
KK Chiong
Parent - - By Niekie3 (***) Date 04-21-2003 08:51
Hi KK

Yes please e-mail me the pictures to:

niekie@frabristruct.com

Thanks
Niekie Jooste
Parent - By kk_chiong (*) Date 04-21-2003 13:47
Niekie,

I had forwards two photo to you and if you did not receive them, please let me know.

Regards,
KK Chiong
Parent - - By kk_chiong (*) Date 04-21-2003 14:27
Hi Niekie,

The e-mail address advice by you seem toi be not working as my photo file that I send earlier is reject and return to me now. Please advice another e-mail address if available.

Thanks & Regards,
KK Chiong
Parent - - By Niekie3 (***) Date 04-21-2003 19:16
Hi KK

Thanks for your efforts with the photo files. How large are they? Try the following e-mail address:

editor@proknownet.com

Thanks
Niekie Jooste
Parent - - By Niekie3 (***) Date 04-21-2003 19:18
Hi KK

I just had another look at my earlier e-mail address and see that I made a typing error. It is supposed to be:

niekie@fabristruct.com

Sorry for the inconvenience.

Thanks
Niekie
Parent - By kk_chiong (*) Date 04-22-2003 06:28
Niekie,

I will forward the photo on Friday as I was outstation and does not operate from my own computer. The photo are at my pc. Be patient.

Regards,

KK Chiong
Parent - - By kk_chiong (*) Date 04-22-2003 06:29
Niekie,
Two photo is about 600KB. Is that OK for me to proceed to send to you.
Parent - By Niekie3 (***) Date 04-23-2003 19:46
This is fine.

Thanks for your trouble

Niekie
Parent - - By G.S.Crisi (****) Date 04-16-2003 00:25
If I had to do the repair you`re talking about I wouldn`t use welding, but another technique I can`t explain here because you won`t understand it without a drawing.
Let me know your address and I`ll send you the details.
Giovanni S. Crisi
Sao Paulo - Brazil
Parent - By kk_chiong (*) Date 04-16-2003 15:30
Dear Giovanni,

I had send my mailing address to your e-mail and you does not recieve them, please let me know. Thanks for your time and information.

KK Chiong
Parent - - By Yuri K Date 04-17-2003 14:47
In case of cyclic loading or vibration, I would recomend to use the Ultrasonic Peening (UP) after repair of the crack by welding. The portable system is available for this purpose. UP could significantly increase the fatigue life of weldments after repair in some cases up to the fatigue life of base metal. We did a few projects where UP was applied for fatigue life improvement after repair of cracks by welding. If you are interested, I could send you a paper "Fatigue Life Improvement of Structural Elements with Fatigue Cracks"

Yuri
Parent - By Niekie3 (***) Date 04-19-2003 12:50
Hi Yuri

I would be interested in that paper. Can you e-mail it to me?

Thanks
Niekie Jooste
Parent - By kk_chiong (*) Date 04-20-2003 14:16
Yuri,

Thanks for your advice and look forward to your paper. Thanks in advance.
Regards,
KK Chiong
Parent - By Sean (**) Date 04-21-2003 16:24
Yuri,

Would you please send me this paper too? Thank you in advance.

Sean
keaysa@hotmail.com
Parent - - By billvanderhoof (****) Date 04-22-2003 03:20
Yuri-
I too would like to read that paper.
Thank you-
Bill
Parent - - By - Date 05-02-2003 15:28
bill
dont forget to send me a coby .
thanks...
ali
domena16@hotmail.com
Parent - By billvanderhoof (****) Date 05-03-2003 05:06
The paper is by Yuri not me so I think it would be more correct to ask him.
Bill
Up Topic Welding Industry / Technical Discussions / Repair crack on 300bar Hydraulic Cylinde

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill