Welding Under the Surface "Every Diver Has A Story to Tell"

Divers face numerous safety challenges and precarious conditions wherever they work. "Safety is always on our minds," said Wheatley, a 26-year veteran of the industry and a certified AXIS welding inspector.

Poor visibility presents a significant challenge for underwaterwelders. Currents, debris, and lack of light in open waters can severely hamper the diver's view. Heavy currents also create situations in which a diver must tie himself into hogging lines, very similar to mountaineering equipment, to avoid being swept away. Trigger fish, stinging Brissel Worms and jelly fish, and other marine life can make an operation even more difficult.

Electric shock is another danger when divers are in the water. Underwater welders can not use alternating currents (AC) and must use direct current (DC) power supplies. A knife-- switch is used to break the current when the diver is notwelding.

Alaska's Cook Inlet is one of the most treacherous places to perform underwater welding because of the 12-18 ft. tide changes and currents among the most dangerous in the world. Wheatley recounted an operation performing repairs in Cook Inlet on an offshore oil terminal damaged by vessels continually striking the structure. "The visibility was horrible. We had to tie ourselves in to avoid being swept away and we had only two-hours of bottom time each day to perform the repairs."

Another time Wheatley's dive suit dissolved while repairing a fishing trawler's fuel tank. The tank had split and would soon begin leaking fuel into Seattle's pristine Lake Union. "We pumped out all the fuel, filled the tank with water, and used wet welding to fix the tank," Wheatley said. "The hydrocarbons in the water actually dissolved the glue holding my suit together."

Have Stinger Will Travel

For subsurface welding applications, simply reaching the worksite can be a challenge. On the job, underwaterwelders travel the world to inland and offshore waters. Diver/welders take on assignments repairing dams on the Nile River, performing subsea pipeline maintenance in the North Sea, fixing a fishing trawler's rudder in Alaska-any-- where they are needed.

Talking about an assignment in Nigeria, Wheatley says, "Years ago I flew to Africa for an operation repairing offshore platforms for Chevron. Local fishermen damaged the platforms by tossing hand grenades into the water to kill the fish. The locals fish near the platforms because that's where the fish school. My assignment was to strengthen and repair the platform by welding structural reinforcement plates on the platform's jackets."

Wheatley said, "The assignment was particularly challenging because of customs issues and the less-than-- welcoming accommodations for the dive team. More than 40 of our divers became sick with malaria, food poisoning or injuries. We sent one malaria victim by MedLife Flight on a Learjet to a hospital in Great Britain."

Underwater Options

Six basic methods of underwater welding are used today. They include dry welding at one atmosphere, drywelding in a habitat, dry chamber welding, dry spot welding, friction stud welding (can be done dry or wet), and wet welding. Only in wet welding is the welder in the water without any physical barrier between the water and the welding arc.

"I think the most significant advances in wet welding were made in the 1970s," said West. "During an international symposium on underwater welding held in London during that time, one underwater contractor reported using more than 144,000 lbs of ferritic wet welding electrodes and more than 4,500 lbs of austenitic electrodes over a period of five years. Today those numbers are a lot higher."

West says wet welds made by qualified welder/divers using qualified wet welding procedures no longer are considered applicable only for emergency salvage operations. Now they are being used for permanent structural applications routinely.

"As a consultant in the wet welding industry for almost 30 years, I regularly witness wet welding qualification tests showing tensile and yield strengths above those obtained with equivalent surface welding electrodes. Although the ductility and toughness were less than that expected from surface welding electrodes, the welds were far from `brittle.' In fact, Navy dynamic tear testing of one ferritic electrode, the BROCO CS-1, showed ductile welds at 28 degrees Fahrenheit." West said.

West added that where base metals are properly selected to avoid hydrogen induced heat-affected-zone cracking, a weld joint can be designed to reduce unit stress such that any decreased ductility will not be a problem.

"Now wet welding is quite common. It represents an important and dependable underwater construction and repair technique," says West.

Industry Standards

Underwater welding codes have been defined and refined during the last 30 years through the work of the American Welding Society (AWS), commercial diving companies, the United States Navy, and commercial dive schools.

Just as the AWS provides technical specifications for surface welding, their Standard D3.6 provides engineers and contractors with information and technical specifications to determine what type of weld to use and how to qualify it. AWS D3.6 describes four types of underwater welds that provide the range of quality and properties currently produced by application of the various methods. The specifications define criteria for properties to be adhered to during welding qualifications and present weld soundness requirements that must be verified in the construction operations. Each weld type must meet all the criteria specified for its class.

Qualifying Procedures

In addition, the AWS requires each diving service company performing underwater welding to qualify a procedure that the company then owns. The qualification variables include depth, consumables, base metal, carbon content and equivalent of the base metal, joint design, joint position, diving equipment used, water temperature, and power supply.

The type of Welding Procedure Specification (WPS) a company wants to qualify depends on the client's requirements. Based on these requirements, and the requirements of the governing code or specification, a WPS is developed and procedure qualification weldments are produced for nondestructive and destructive testing. Upon satisfactory completion of the weldment testing, the company receives approval of the qualification test results from the clients and associated governing code or specification body. The WPS can then be used to qualify the needed number of diver/welders for the job.

"Underwater welding, dry or wet, is a constant learning process brought on by technological advances, stricter governing codes, and specifications resulting in an increase in demand due to proven cost savings in many commercial and military applications," says John Smith of Phoenix International Inc., Bayou Vista, LA.

Utilizing its 10 dry and three wet underwater welding procedure specifications approved by Naval Sea Systems Command (NAVSEA), Phoenix International has performed worldwide ship repairs on a broad spectrum of base materials ranging from mild steel to high yield strength HY80 steel, stainless steel, and non-ferrous alloys. The company has an additional four dry and one wet underwater welding procedure specifications pending NAVSEA approval, which would expand Phoenix International's ability to meet the increased demands of the U.S. Navy. In addition to the 13 NAVSEA approved welding specifications, Phoenix has a dry and a wetunderwater welding procedure approved by the American Bureau of Shipping.

Wide-Ranging Operations

 

"The scope of jobs that require underwater welding is enormous and varied," said Wheatley. "We may be called on to add strength to an underwater structure like a bridge or platform or to make a repair in a nuclear power plant."

The bulk of underwater operations is most concentrated in a few key industries: the petroleum business for offshore platforms, pipelines and ships; the United States Navy for ships and facilities; and structural and marine engineering companies. Applications also include construction, repair and maintenance of port and harbor facilities, sheet piling, seawalls, bridges, water district facilities, underwater pipelines, and more. Salvage companies and commercial and pleasure shipping also utilize wet welding in their operations.

Wheatley noted the number of operations calling for welding in inland waters often is overlooked.

The Northwest salmon, many species of which are endangered, can thank the skill of underwater welders for construction and maintenance of many fish by-pass systems running along the Columbia and Snake Rivers in Washington and Idaho. Elaborate structures allow young salmon (smolts) to journey to the Pacific Ocean while avoiding the mighty dams' deadly turbines. Years later, as they return to spawn and die, the fish ladders assist the salmon in navigating the huge man-made changes in the river to reach their native spawning grounds.

"The new Rocky Reach Dam bypass system in Washington state will require more than 2000 linear feet of underwater wetwelding for attachments of the walls, pile caps, and girders. Both slot welds and fillet welds will be used," said Wheatley.

"It is a tremendous project to assure the salmon a path around the dam for their migration."

Advanced Training

Underwater welders prepare for their careers by training at the commercial dive company's location or training first at a school offering courses to familiarize divers with what to expect inunderwater welding environments. Schools are sprinkled across the United States from Seattle to New Jersey.

At the College of Oceaneering in Wilmington, California,diver/welders train with underwater welding instructor Duke Ogden. The college's course covers surface-supplied air diving and then students advance to one of three specialties. The specialties offered include: an underwater welding and cutting program-- WeldTech; an underwater inspection program-SpecTech; or one in which students become certified medical technicians and receive training in the hyperbaric treatment of dysbaric illnesses-MedTech.

Ogden says students must first learn about the physiological effects of underwater activity on the human body, then add maintenance of the diving equipment, hyperbaric procedures, and chamber operations. Each student advances only as he proves he's mastered a set of skills. All students who want to take the WeldTech specialty course must be qualified topside welders before entering the program.

"Our objective is to train student diver/welders in topside and underwater welding to a degree of proficiency that when they leave the College and apply for a job with a diving contractor, they have the skills and requisite mental attitude to be a quality employee," Ogden said. "It is important to have students leave the program with some outstanding certifications on their resumes and a strong list of skills and abilities." He adds, "Underwater welders must be prepared to do it all-fit up, grinding, clamping, tacking, reading the blueprints, and performing the welding."

Ogden said there are times the diver/welders cannot attend the program in California and commercial dive companies hire an instructor to come to them. In the last few years Ogden has traveled to Egypt, Singapore, and Venezuela to train diver/welders involved in maintenance and repair operations.

Divers also must qualify with a commercial diving company using the company's qualified welding procedures and must continually upgrade and maintain their skills by performing welding or being in training every 90 days.28

Special Equipment

Equipment developed specifically for underwater welding is used in the wet welding process. Specialunderwater electrodes are used by the divers, along with electrode holders exclusively designed for use in the wet. As with surface welding, a welding lens is used to protect the diver from ultraviolet light, and personal protective gear such as waterproof gloves are used to avoid electric shock.

Gary Maines, vice president of Broco Inc., Rancho Cucamonga, CA, says years of research and development have made wet welding equipment state-of-the art. "Thirty years ago divers made their own electrodes, and inconsistent quality presented safety and durability issues. Now divers can select a premium wet weldingelectrode, such as our SofTouch, that allows welding in any position and produces welds that consistently meet or exceed AWS specifications for Type B welds," Maines said. "Or, when operations for a less critical application, they may use a high quality economy electrode such as our EasyTouch. Divers now have so many more choices."

Maines said divers today expect further enhancement in the quality and weldability of underwater weldingconsumables, and supplier companies are continuing their research and development efforts. "One of the projects underway at Broco is an underwater wire-feed welder."

Wet Welding a Popular Choice

"Companies are looking for high quality results in an economy that demands efficiency," West says. "That's why wet welding is a popular choice of welding engineers as they specify requirements for applications around the globe."

Wheatley says the choice of wet welding will keep divers busy and grow the need for quality welder/divers. "However, underwater welding is not for everyone. It's a special profession."

Sumber : Ferry, Marylou. "Welding Under the Surface "Every Diver Has A Story to Tell"". 28 Januari 2014. http://search.proquest.com/docview/213304629?accountid=31562