Monday, August 2, 2010

RE: [MW:6238] FW: 6138] Inconel 690 Tube Bending

Mr Hegde,
Thou procuring straight tubes are economical, it is advisable to procure as U bend from the mill. in this this case the mill will do heat treatment once after forming of bends.
 
BR


From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of pgoswami
Sent: Saturday, July 31, 2010 5:08 AM
To: materials-welding@googlegroups.com
Subject: [MW:6212] FW: 6138] Inconel 690 Tube Bending

 

Mr Hegde,

 

Inconel 690 (UNS N06690) is an all austenitic alloy which is covered under Sec-II Part-B,SB-163.  Krupp Nicrofer 6030  is the product of Thyssen Krupp VDM  , one of the key players for this type of alloy products. Although being austenitic,  Inconel 690 alloy have fairly high UTS and  could work harden considerably while cold bending. Hence manufacturer recommends post forming heat treatment as follows:-

 

Cold working:- For cold working the material should be in the annealed condition. Nicrofer 6030 has a higher work-hardening rate than austenitic stainless steels. This should be taken into account when selecting forming equipment. Interstage (Intermediate) annealing may be necessary with high degrees of cold forming. After cold working with more than 10% deformation soft or solution annealing is required before use.

Soft annealing of Nicrofer 6030 should be carried out in the temperature range 1020 to 1070 °C (1870 to 1960 °F), preferably at about 1040 °C (1900 °F).

Solution annealing for improved creep strength is carried out at 1080 to 1150 °C (1980 to 2100 °F). Water quenching or rapid air cooling is recommended for thicknesses above about 1.5 mm (0.06 in.) and is essential for maximum corrosion resistance.

 

If the design code for the exchangers is ASME ,Sec VIII, DIV-1, then the requirements of UNF-79 would apply for post forming  heat treatments, provided the tubes are bent in the shop.

 

Should the tubes be procured in finished  condition( U-Bundle) from the mill  then the supplementary conditions of SB-163 would apply.

 

The  O  D of the tubes and wall thickness are very small. Hence without proper tube bending devices U-bent areas could get flattened. See the attached Special Metals brochure for your added reference.

 

Thanks.

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Engineer/Specialist

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net 

www.opg.com 

  


From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of PB HEGDE
Sent: Tuesday, July 27, 2010 2:11 AM
To: materials-welding@googlegroups.com
Subject: [MW:6138] Inconel 690 Tube Bending

Dear Friends

 

I have a query and request you to give your opinion

 

a)      One of the  Heat exchangers, we want to use  U tubes  of Inconel 690 having  OD of 13mm and 19mm  with thk of 1.2mm

b)      Straight tubes shall be purchased and bending shall be carried  in house  or at tube manufacturer

c)       I want to know does it require any solution annealing after U bending ? and if Yes  what will be cooling media and method to avoid flattening of tube near bend

d)       What are the testing require to ensure correct metallurgical , physical and  mechanical properties

 

Warm regards

 

Hegde P.B.

+919714714803

 



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