Commercial Diving

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Commercial Diving is a branch of professional diving where the divers are paid and the work is for profit.

Commercial diving includes these types of diving activities:

• Offshore diving: Often used in the oil and gas production industries, this type of diving is needed to construct and maintain oil rigs and pipelines.
• Inland and inshore diving: This type of commercial diving is often used in the support of civil engineering and harbours.
• Nuclear industry diving: diving in radioactive conditions
• HAZMAT diving : diving in the presence of hazardous materials
• Dive instructors: Diver training for reward

Other types of professional diving are carried out by non-profit making organisations. These include:

• Scientific and archeological diving: carrying out underwater research
• Media Diving: Organizations involved in underwater journalism and movies.
• Military diving - covert infiltration and underwater engineering by land-based forces
• Naval diving - ship maintenance and repair, mine clearance by ship-based forces
• Police diving - collecting evidence from underwater
• Rescue and Public Safety Diving

Professional diving is different from recreational diving in three main ways: the diving equipment used, the nature of underwater activities and the need to adhere to stricter safety legislation; however, amateur divers do sometimes do purposeful work underwater using commercial equipment and techniques.

Common purposeful amateur diving activities include:

• Dive instructors: diver training
• Scientific and archaeological diving: carrying out underwater research

Professional equipment

Professional divers use different types of equipment, with the decision on the equipment required depending on a number of factors, mainly the depth the diver will be working at, and the length of time they will be spending underwater. Certain applications may require specific equipment due to space constraints or contamination.

Most professional divers using SCUBA equipment will use a full face diving mask which covers the whole face, and combines a diving regulator and diving mask in one unit. Full face masks often have communication equipment which allows the diver to stay in contact with the surface, which is a legal requirement in some countries.

Typically divers will use a diving helmet which supplies air from the surface, and depending on the water temperature, will either use a wetsuit, a drysuit or where the water is exceptionally cold, a hot water suit which circulates warm water from the surface around the diver.

For long or deep dives, surface supplied diving equipment is used; a long hose, called an umbilical connects the diver to the surface and supplies breathing gas. Depending on the diver's dress, the umbilical may include hoses for air and hot water for the diving equipment, air for any pneumatic tools, communications and electrical power supply cables for any voice, video and lighting equipment the diver has fitted to his helmet or full face mask.

For short and shallow dives, a diver may use SCUBA equipment, but in some localities, it is a safety requirement that commercial divers be able to communicate by voice with their support crew on the surface.

SCUBA

This section outline of the use of SCUBA equipment in commercial diving. For the main article, see SCUBA.

SCUBA equipment can only provide a limited amount of breathing gas for the diver, and there is no easy way to change an empty diving cylinder for a full one while underwater, so SCUBA dives are generally short in duration. The time a diver can spend underwater breathing from a high pressure cylinder is determined by the size of the cylinder, the depth at which the diver is working, and his breathing rate. As commercial divers tend to work harder underwater compared with leisure divers, the time a cylinder of breathing gas will last is reduced.

SCUBA may be used as the primary breathing equipment of a dive or as a 'bail-out' for surface supplied diving. The same technology is used in both cases, but SCUBA is generally used as the primary equipment when the dive is shorter, less challenging and simpler than one requiring surface supplied equipment. The purpose of a SCUBA bail-out is to provide an emergency reserve should the diver's breathing gas supply from the surface fail.

Surface Supplied Diving

For the main article, see Surface supplied diving.

Surface spplied diving equipment, which provides the diver via an umbilical, is used mainly for longer, deeper and more demanding dives. The main advantages are that large quantities of gas can be stored at the surface, the surface personnel have indirect physical connect with the diver, they can reduce the diver's workload by controlling gas mixes and warm water heating and communications can be provided through the umbilical.

Saturation or Closed Bell Diving

For the main article, see saturation diving.

When doing very long, deep and demanding dives, the divers use "saturation" decompression strategy with surface supplied diving equipment and diving bells.

Types of commercial diving

Offshore Diving

Typically offshore diving takes place under oil platforms, on Subsea Templates or Wells and the pipelines that connect them to their shore installations.

Inland and Inshore Diving

Inland or Onshore Diving is very similar to offshore diving in terms of the nature of the work involved: construction and survey work mainly. Typical activities for onshore companies are surveying of water storage tanks, reservoirs and pipelines, construction work on canals and facilities in lakes and estuaries, pontoons, bridges etc with most work being undertaken in fresh water as opposed to salt water.

Onshore divers typically earn less per hour than their colleagues who work offshore, but more onshore divers can return home each night, whereas offshore divers may spend weeks offshore.

Generally, the same equipment as used in the offshore industry, with SCUBA a little more common as depths the diver will often be working in quite shallow water, or in locations where surface supplied equipment is difficult to use, water tanks for instance.

Nuclear Industry Diving

Nuclear Diving is a very specialised industry with few companies and divers authorised to work inside nuclear power stations. The bulk of the work involves maintenance of the cooling ponds used to store radioactive waste, and as they tend to be made of stainless steel, they require skilled divers to make any repairs.

This diving work is normally very safe, with the major hazard being radiation instead of boats, currents and falling objects offshore and inland divers face, however due to the extremes that the divers work in, thermal stress and radiation poisoning are very real dangers that need special training and equipment to overcome.

Nuclear divers will only ever use a metal based diving helmet as fibreglass helmets absorb radiation and could be unsafe after multiple dives, metal helmets don't face this problem and can be used again and again. The divers will always wear a rubber drysuit and the diving helmet will mate directly to the drysuit creating a water and air-tight environment for the diver. Typical helmets used include the Desco 'Pot', which is made of Copper.

In certain cases, the diver will need to wear a cold water suit, a special canvas coverall which floods the outside of the divers air-tight rubber drysuit with cold water, counteracting the dangerous temperatures of the cooling pond.

Finally, and most importantly, the diver will be fitted with a dosimeter which will determine the length of time the diver can work in the environment by calculating the levels of radiation he/she has been exposed to.

HAZMAT Diving

HAZMAT Diving is widely regarded as the most dangerous sub-branch of the commercial diving industry, employing highly skilled and experienced staff.

Typical work involved diving into raw sewage or dangerous chemicals, such as paper pulp, liquid cement or oil sludge, to do this, divers need to be vaccinated against diseases such as hepatitis and tetanus, the dive company needs to have specialist plans in place for decontamination of the diver and equipment following a dive, and procedures for recovery of the diver if something goes wrong.

The main tasks a diver can be found to be doing include essential maintenance of underwater valves and sluice gates, repairs to damaged pipelines, and pollution control work to contain, control and clean up after a pollution incident. Some divers are required to dive into landfill sites in order to maintain the pumping equipment, which prevents landfill sites from filling up with rainwater, other divers can be found welding inside live sewers or working in septic tanks.

Sewer diving is often considered the most dangerous of all the HAZMAT jobs due to the diseases contained in raw sewage coupled with the fact syringes and glass find their way into the raw sewage, creating risks of both contracting diseases should the diver be injured by a needle, and also damaging the drysuit.

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Divers working in an environment harmful to their health will always wear a full drysuit with thick gloves which are attached directly to the suit, the helmet and boots will also attach directly to the drysuit, this allows the gloves, boots, suit and helmet to be pressured in order to prevent ingress of liquid should a puncture occur. Normally to achieve this, a diver will use a free flow diving helmet which continually supplies enough air for the diver to breathe plus an additional amount to pressurise the suit, a free flow helmet has a much lower chance of leakage through the exhaust valve compared with a demand helmet where the exhaust valve is dormant during the inhalation stage of the diver breathing.

The drysuit will be made from a material resistant to whatever hazard the diver faces, normally this will see the diver wear a vulcanised rubber drysuit, but occasionally a neoprene or tri-laminate suit is required. Often, a diver will wear additional protection over his drysuit to decrease the chance of a puncture, leather and nylon coveralls frequently being used in addition to PVC Chemical boiler suits.

Scientific and archaelogical diving

For scientific and archaeological applications for which diving is needed see:

• Underwater archaeology
• Marine ecology

Media diving

Dive instructors

See also

• Diving activities

External links

• [Life of a nuclear diver]

 

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