Surface quality wet welding
 'A' Class above the rest

Wet welding has always been seen as the poor relation to conventional dry, surface welding but should this really the case? The wet welding process is the most widely used method for welding underwater, its versatility and cost effectiveness can provide a viable and desirable alternative to the more traditional methods of repairs to underwater structures such as dry docking, habitat welding or clamping. Wet welding systems can be mobilised in hours rather than days and repairs can often be completed whistle structures or vessels are still in service.
 
As an aid in providing quality assurance the American Welding Society (AWS) developed a welding standard, the AWS D3.6 Specification for Underwater Welding. This specification, which was first published in 1983, was intended to provide those with a requirement for underwater welding a choice of weld quality, on a fitness for purpose basis, taking in to consideration the state of the art of underwater welding at that time, and included both dry hyperbaric and wet welding. The specification has subsequently been revised several times but still sets out four classes of welds identified as class A, B, C or O. These classes are broadly defined as: class 'A' welds which are intended to be comparable with above water welds by virtue of specifying comparable properties and testing requirements. Class 'B' welds which are intended for less critical applications where lower ductility, greater porosity and larger discontinuities can be tolerated. Class 'C' welds which are intended for applications where load bearing is not a primary consideration and satisfy lesser requirements than class A, B and O. And finally class 'O' welds which must also meet the requirements of another code or specification.
 
In recent years the wet welding process has seen dramatic improvements in weld quality which has broadened its potential to encompass underwater welding projects for which it previously could not be considered. With the advent of new wet welding electrodes (Hydroweld FS) and the development of new wet welding techniques combined with modern welding power sources and equipment the process can now provide weld quality comparable to that expected on the surface. Whilst class 'B' and 'C' welds are easily achieved with the wet welding process, the production of class 'A' welds has not, until recently, been an option because of the difficulties in meeting the all of the mechanical and visual property requirements detailed in the specification.

Historically wet welds have lacked ductility, have high hardness values, suffered from hydrogen cracking and suffered from brittleness. Some manufactures of wet welding electrode often quote-individual properties of their electrodes as being class 'A' acceptable such as a radiography report or tensile strength but are still a long way from meeting class 'A' weld specification. Lack of ductility is still one of the major faults with many electrode manufactures quoting less that 9% elongation on all weld metal tensile tests and impact tests well below what is required by class 'A'.

In September 1999 a group of enterprising diving contractors joined forces and embarked on an ambitious wet welding programme, which proved to be an historic first. The programme included an intensive wet welder-training programme, the production of welding procedures and finally the completion welder qualifications. But unlike anything before, this programme was aimed at pushing the boundaries of wet welding technology one step further. The aim was to become the first diving contractors in the underwater ship repair industry to offer 'surface quality, structural wet welds' as specified in the AWS D3.6M: 1999 Specification for Underwater Welding for Class 'A' welds. Thus producing a weld quality, which should be acceptable as permanent wet welded repair method within the shipping industry.
 
The principal companies involved were Miami Diver inc. (USA), Trident BV (Netherlands) and Cores Diving (Canada). Dedicated to providing a quality service within the ship repair industry, these companies consistently strive to be leaders in their field. As part of there ongoing self-imposed strive for excellence they employed the services of Hydroweld (UK) a company who is recognised internationally as leaders in the field of wet welding, to provide them with the wet welding technology required to fulfil their goals.
 
It was Hydroweld's reputation that convinced Kevin Peters of Miami Diver Inc. that if they were going to succeed they needed the expertise that Hydroweld had to offer. Hydroweld wrote the formal Wet Welding Procedure Specification (WPS) which included the use of Hydroweld FS wet welding electrodes and put together an intense wet welder-training programme. Then finally assisted in the qualification of the welding procedures and welder qualifications.

The project was completed at Miami Diver Inc. underwater training facilities in Miami, Florida where a confident Kevin Peters, on completion of the 10 day training programme, made arrangements for six of the major classifications societies to attend and witness the welding procedures, welder qualifications and testing of the coupons.
 
These independent witnesses including Lloyds Register of Shipping (LRS), American Bureau of Shipping (ABS), Det Norske Veritas (DNV), Bureau Veritas (BV), Rina and Germanisher Lloyd (GL). Their attendance was required to ensure the welding procedures, welder qualifications and testing of the coupons complied with the AWS D3.6M-99 Specification for Underwater Welding Class 'A' weld standard. Kevin Peters also arranged for an independent accredited test house to complete the sophisticated testing of the coupons. The test house provided the data from the testing and together, with the classification societies, confirmed that the specimens complied with or exceeded the requirements of the AWS D3.6M: 99 for Class A welds.

The welding procedure coupons were completed in three positions 2F Horizontal (PB), 3F Vertical (PG) and 4F overhead (PD) positions. In addition a 20 mm Grove/Butt weld (for the Charpy impact test and all weld metal tensile test) and a longitudinal fillet weld -shear strength test specimen was produced in accordance with the specification. The welder qualifications were completed in the 3F vertical and 4F overhead positions.
 
Kevin Peters of Miami Diver acknowledges that the Hydroweld FS wet welding electrode was crucial to the success of the project ' Other wet welding electrodes lack ductility, one of the biggest obstacles in qualifying class 'A' welds is meeting the requirements of the all weld metal tensile test. Most weld welding electrode can only manage 6% - 9% elongation, the specification requires a minimum of 14% the results from Hydroweld FS gave us 17% which is comparable to surface welds. All of the other testing either met or exceeded the requirements of class 'A' welds including the visual, macro examination, hardness, fillet weld shear, and Charpy tests.
 
The successful completion of the welding procedures and welder qualifications to the AWS D3.6M: 99 Class A welds proves that surface quality wet welding can be achieved. This represents a significant step forward and one that may result in wet welded repairs in the merchant shipping industry being accepted as permanent.  Hydroweld offer speciality welding services to the industry throughout the world and strive to improve the reputation of wet welding which has historically been misused and applied.