e-Weldone Newsletter January 2011 Vol. 24
Supergen 320
ADVANCES IN WELDING CONSUMABLES FOR OIL, GAS AND POWER SECTORS- PART II
 
INTRODUCTION
In the last issue, we reviewed the importance of development of welding consumables for meeting requirements of special service conditions in the Oil, Gas and Power industry. Development of consumables for welding carbon steels for critical applications in these industries was described in detail. In this issue we will discuss the development of welding consumables for welding of alloy steels and stainless steels for this sector.
 
CONSUMABLES LOW ALLOY STEELS
Low alloy steels are widely used for low, high temperature and high strength applications in all the three industries, particularly in the power industry. In the power industry a number of low alloy steels are used for elevated temperature applications. Over the years a variety of quality requirements have been introduced in these groups of weld metals. Apart from the chemical and mechanical properties, today emphasis is on properties like toughness, embrittlement, creep, hot strength which are very essential for satisfactory performance in service.
 
Consumables for Cr-Mo steels
Cr-Mo steels find use in elevated temperature applications in Oil, Gas and Power industries. A number of these steels with varying amounts of Cr, Mo and other elements are used to manufacture components. Table 1 details the various consumables in this group and their typical weld metal chemistries. While some of the grades have been in existence for a long time, many new versions have been introduced to suit specific needs. These are
  • Weld metals with temper embrittlement resistance
  • Weld metals with hardness control
  • Weld metals with properties after prolonged PWHT
  • Weld metal meeting Inter - granular corrosion (IGC) test requirements
  • Weld metals with creep properties
  • Non-Synthetic types
  • Special grades with additions of V, W, B, N, Nb, Ti
Table 1: Cr-Mo weld metals
AWS classification Typical weld metal major elements
E8018B2 0.07C-1.25Cr-0.5Mo
E9018B3 0.07C-2.25Cr-1Mo
E8018B6 0.07C-5Cr-0.6Mo
E9018B8 0.06C-9Cr-1Mo
E9018B9 0.06C-9Cr-1Mo-0.4Nb-0.04N-0.5Ni-0.2V-0.03Al
E7018B2L 0.045C-1.25Cr-0.5Mo
E8018B3L 0.045C-2.25Cr-1Mo
Special type To meet step cooling, J,X factor and temper embrittlement resistant
Special type To meet prolonged PWHT
 
Weld metals with temper embrittlement resistance
Cr-Mo steels get embrittled when exposed for long periods in the temperature range of 400-500C.Tramp elements like P, As, Sb, Sn are the root cause for this problem. By controlling the tramp elements it is possible to overcome this problem. This is done by using two parameters X and J factor as detailed below
 
Factor Formula- Elements in %wt Requirement
Bruscato X factor for Base and weld metal (10P+5Sb+4Sn+As) / 100 <10
Watnabe J factor for base metal (Mn+Si)+(P+Sn) 10000 <80
 
A step cooling heat treatment is also performed to determine the susceptibility of the base and weld metals to this problem. All these go to show the stringent quality standards within which consumables are being developed today to meet the industry needs.
 
Weld metals with hardness control
Weld metal, HAZ and base metal hardness are important factors which determine the performance of the welded joint in service. Hence in many situations the weld metal chemistries are controlled to lower carbon levels to achieve lower hardness. Table 2 gives the different grades of Cr-Mo weld metals with lower carbon.
 
Table 2: L- versions of Cr-Mo weld metals
AWS classification Typical weld metal major elements
E7018B2L 0.045C-1.25Cr-0.5Mo
E8018B3L 0.045C-2.25Cr-1Mo
E8018B6L 0.045C-5Cr-0.5Mo
 
Weld metals with prolonged PWHT
Most of the Cr-Mo steels are subjected to Post weld heat treatment after welding to relieve the stresses. The AWS specifications also specify the PWHT for various weld metals. But in actual practice many times the weld metals are subjected to prolonged, repeated heat treatment cycles in which the standard AWS testing may not give the correct picture. Therefore many weld metal specifications, today, specify many changes in the PWHT. In order to meet these requirements the weld metal compositions have to be adjusted to optimum levels so that the desired properties are achieved. Table 3 gives details on some of the heat treatments for weld deposits from a few different electrode types.
 
Table 3
AWS classification Heat treatment details
E 8018 B2 690 C FOR 2 HRS
E 8018 B2 690 C FOR 12 HRS
E 9018 B3 740 C FOR 4 HRS
Cr-Mo-V type 690 C for 2 hrs + WQ from
940 C + tempering at 720 C
E7018 B2L 720 C FOR 2 HRS
E 8018B 3L 710 C FOR 2 HRS
E 9018 B9 760 C FOR 4 HRS
 
Creep Properties
For any elevated temperature application, creep data is very important. Providing creep data for weld metal has now become a regular feature, at least for normal grades. However generation of this data is  time consuming  and also  expensive.
 
Non-Synthetic types
SMAW electrodes can be made with carbon steel core wire or with alloyed steel core wire. In Cr-Mo steels, especially at higher alloy levels, it is preferable to use non-synthetic types as they produce consistent properties. Today, non-synthetic electrodes are available even in 9Cr-1Mo types, which produce consistent mechanical properties.
 
Special grades with additions of V, W, Nb, N, B, and Ti
With the operating temperatures and pressures going higher and higher and with  increasing concern for increasing operational efficiency, controlling emissions, super and ultra super critical boilers are being considered which use Cr-Mo steel with additions of the above elements. Materials like P91, P911, P92, P23, P22V, and P24 belong to this category. Welding consumables meeting these requirements are under development and testing. In future many power plants will use these types of consumables.
 
CONSUMABLES FOR STAINLESS STEELS
Stainless steels are used widely in Oil, Gas and Power industries with the former two using them in good quantities. A variety of grades are used and they have been standardized for many applications. The common varieties like L grades, stabilized grades and their combinations have been in existence for quite some time now. 
 
Inter granular corrosion (IGC) test
This is a test to ascertain the suitability of austenitic stainless steel material under corrosive conditions. A pass or failure in this test will forecast the behavior of the material under actual service condition. Normally the IGC test is conducted as per ASTM 262 practices like A-B-C-D-E. All these tests are different and are used for different conditions. 
 
Cryogenic  service applications
For some applications, the stainless steels and the resultant weld metal have to withstand temperatures of up to -196 DEG C. Consumables have been developed for this application and some of them are detailed in the last table given below.
 
AWS Properties
E308L-15 Meeting impacts and lateral expansion at minus 196C
E316L-15 Meeting impacts and lateral expansion at minus 196C
ER308L --do--
 
Duplex and Super Duplex stainless steels (DSS and SDSS)
Of particular interest to us at this juncture are the duplex and super duplex stainless steels which are increasingly used in oil and gas industries especially for components which are subjected to stress corrosion cracking. Table 4 shows the details of the popular weld metal grades for these materials and the base materials on which they can be used. Indigenous developments are still in progress to deliver these weld metals with detailed corrosion data and also to understand the effect of various welding variables on these properties.
 
Table 4: DSS-SDSS materials (Typical major elements)
Property E2209 E2553 E2595
C 0.03 0.04 0.03
Cr 22 25 25
Ni 9.5 7 9.5
Mo 3 3.5 4
N 0.12 0.2 0.25
Cu -- 2 1
W -- -- 0.7
Mn 1.5 1 2
 
H versions of standard grades
The higher carbon versions of 308, 347 are now being considered for their elevated temperature properties. New weld metals with higher carbon in the range of 0.04-0.08 are now available for these materials.
 
CONSUMABLES FOR NICKEL ALLOYS
Nickel alloys form one of the important material groups used in these industries. Many consumables have been developed to meet the welding requirements of this group. Table 5 gives details of some of the consumables in this group.
 
Table 5: Nickel alloys (Typical major elements)
Property ENiCrFe2 ENiCrFe3 ENiCrMo3 ENiCrMo6
C 0.05 0.05 0.05 0.05
Mn 2 7 1 max 3
Fe 8 7 5 7
Cr 15 15 22 15
Nb+Ta 2 2 4 1.5
Mo 2 -- 9 7
Ni 62 min 59 min 55 min 55 min
Ti -- 1 max --  
W -- -- -- 1.5
 
Grade Typical application
E NiCr Fe2 Dissimilar metals, low temp and high temperatures up
to 820C; for welding B163, B167, B168, UNS  N 06600
E NiCrFe3 Dissimilar metals, low and high temperature
applications up to 480C; for welding UNS N 06600
ENiCrMo3 For welding UNS N 06625, B 443,444,446;
dissimilar metals; for temperatures from cryogenic to 540C.
ENiCrMo6 Popularly used for welding 9%Ni steels;
A333,334,353,522,553, UNS K 81340
 
CONCLUSION
As we saw earlier, the Oil, Gas and Power industries offer a number of challenges for welding by constantly using improved and newer materials. This has been the constant factor fuelling the development of a host of new and modified consumables to suit the application and also the service condition. Thanks to these cooperative efforts, today we have a wide spectrum of welding consumables meeting many service conditions.
 
Some Ador Welding Ltd. consumables for welding alloy steels and stainless steels in Oil, Gas and Power industries and tests performed.
Please click on the electrode name to know more about its properties
 
AWS CODE PROCESS AWL
PRODUCT
NAME
NACE
TEST
IGC
TEST
IMPACT
AT (-196
DEG C)
C.T.O.D
TEST AT
(-10 DEG C)
E 7018 G SMAW TENALLOY
Ni (Spl Batch)
N.A. N.A. N.A. DONE
E 8018 G SMAW TENALLOY
60 NX
(Spl Batch)
N.A. N.A. N.A. DONE
E 347 - 16 SMAW SUPERINOX
1B
DONE N.A. N.A. N.A.
E 308L - 15 SMAW SUPERINOX
1C 15(LT)
N.A. PRACTICE
E
DONE N.A.
E 316L - 16 SMAW SUPERINOX
2C
N.A. PRACTICE
E / B
DONE N.A.
ER 308 L TIG TIGINOX
308L
N.A. PRACTICE
E
DONE N.A.
ER 316 L TIG TIGINOX
316 L
N.A. PRACTICE
E / B
N.A. N.A.
ER 308 L MIG MIGINOX
308 L
N.A. PRACTICE
E
N.A. N.A.
ER 309 L MIG MIGINOX
309 L
N.A. PRACTICE
E
N.A. N.A.
ER 316 L MIG MIGINOX
316 L
N.A. PRACTICE
E
N.A. N.A.
ER 70 S 2 TIG TIGFIL
70 S 2
DONE N.A. N.A. N.A.
ER 70 S 2 TIG TIGFIL 70 S
2 (SPL)
DONE N.A. N.A. N.A.
EH 10K
(WIRE)
SAW AUTOMELT
EH 10 K
UNDER
WAY
N.A. N.A. N.A.
B41
(FLUX)
FLUX AUTOMELT
B 41
UNDER
WAY
N.A. N.A. DONE
ER 308 L SAW SUBINOX
308 L
N.A. PRACTICE
E
DONE N.A.
S 33
(FLUX)
FLUX AUTOMELT
S 33
N.A. PRACTICE
E
DONE N.A.
ER 309L SAW SUBINOX
309 L
N.A. PRACTICE
E
N.A. N.A.
ER 316L SAW SUBINOX
316L
N.A. PRACTICE
E
N.A. N.A.
 
To know more about the special requirements and availability of welding consumables in the Oil, Gas and Power  sectors please contact us at cmo@adorians.com. or visit us at  www.adorwelding.com
Motor Generator Welding Set
Supergen 320
Ideal for welding with cellulosic electrodes for cross country pipelines and thermal/nuclear power plants
Three Phase motor as prime mover
DC Welding generator of a special patented design
Positive protection against overload and single phasing
 
ADOR Institute of
Welding Technology
Ador Institute of Welding Technology
Course for Quality Assurance
& Control of Welding (QA-1)
17th - 20th Jan. 2011
 
Refresher Course in
Welding Technology (SC-1)
7nd - 12th Feb. 2011
 
Welding Procedures & Qualifications (QA-2)
14th - 16th Feb. 2011
Visit AWL Stall No. 35 & 36 at The India Show 2011 at Suntec International Convention & Exhibition Centre, Singapore during 14th to 16th Jan., 2011.
 
Visit AWL Stand No.920 at Steel Fab 2011 at Expo Centre Sharjah, UAE 17th to 20th Jan., 2011.
 
Happy New Year
 
 
 
Project Engineering
Solutions
ADOR Institute of
Welding Technology
Welding &
Cutting Solutions
Centre for
Engineering Excellence
Ador Welding Limited - Welders To The Nation
www.adorwelding.com
cmo@adorians.com Contact us