Safety code for the hottest underwater welding ope

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Safety code for underwater welding operation

underwater operation refers to the activities of researchers, workers or military personnel who are completely submerged in a pressurized environment while engaged in a specific task. Underwater operations include: installation and recovery of caissons; Install wharf protection; Inspect dikes and embankments; Laying various underwater cables; Install navigation equipment; Salvage the sunken ship; Charting; Repair offshore oil drilling platforms and many construction related operations (such as underwater concrete pouring, underwater welding, repairing cracks in hydraulic structures); Digging water, especially promoting the complete separation of state-owned capital ownership and enterprise management rights; Construction of undersea houses; Scientific exploration, etc

I. safety analysis and accident causes of underwater operation

when people see the scenes of divers swimming freely in the water with masks on their heads, gas cylinders on their backs, and duck fins on their feet from TV or movies, they will think that diving operation is a very pleasant activity. In fact, it is indeed a dangerous working environment. If you list the types of diving accidents, there are as many as 16, ranking first in all kinds of operations. They are: decompression sickness; Bleaching; Crushing injury; Air plug; Oxygen spasm; Nitrogen anesthesia; Carbon dioxide poisoning or suffocation; drown; Water activities are blocked; Hyperbaric nerve syndrome; Shock wave damage in water; Inflation (also known as hypotension); "Water shock" and frostbite caused by low temperature; Halo; Infected; Damage to marine life

in order to overcome the pressure barrier, pressurize the air to balance the static pressure of water, and realize the environment in which people can work for a long time in deeper water. No matter what type of diving equipment, the air pressure in the lungs of operators must be very close to the air pressure in the surrounding environment. During diving or pressure boosting period), the hazard is "crush injury", which can seriously damage the inner membrane of the air containing sinus and tympanic membrane, and sometimes damage some body surfaces at the uneven folds of the diving suit. When a diver is in deep water, once the hard helmet loses pressure, it will produce a fatal squeeze. The hazards during the floating period (or decompression period) can be roughly divided into two categories

1. Barotrauma

the injury site is any air containing cavity, because the pressure in the cavity cannot be balanced with the pressure of the surrounding environment, resulting in the destruction of tissues, among which the most common is the injury of the middle ear and anterior organs. However, the fatal injury is still the "air gun", which is caused by the diver diving when the lungs are inflamed and lack the ability of original innovation, resulting in the rupture of the alveolar cavity and the invasion of gas into the blood circulation system

2. Decompression sickness

the increase of ambient air pressure will increase the amount of nitrogen dissolved in the air by human blood. If the floating period returns to the normal atmospheric pressure environment too quickly, just like the result of opening the soda or champagne bottle cap, a large number of bubbles are formed in the blood. The main symptoms are: pain in the big joints of one or several limbs and marbling on the skin

II. Safety analysis and accident causes of underwater welding operation

at present, there are 20 underwater welding methods. However, in essence, land welding methods are still used, but in order to solve the basic problems of underwater welding, different means and devices must be adopted. Generally, underwater welding methods are divided into three categories: wet, dry and local dry underwater welding

underwater environment makes the welding process much more complicated than land welding. In addition to the welding technology itself, it also involves many factors such as diving operation. The following problems have a direct impact on the welding process:

① poor visibility (the absorption, reflection, refraction and other effects of water on light), which hinders the normal play of diving welding technology

② the quenching effect of water on the weld is prone to high hardness hardened structure

③ the hydrogen content of underwater welds is generally high, which is easy to cause hydrogen embrittlement or white spots, brittle fracture spots and cold cracks

the accident causes of underwater welding are as follows

(1) explosion accident caused by the presence of dangerous chemicals, ammunition, etc. in the welded and cut components, or the containers and pipelines of flammable and combustible materials that have not been safely treated during welding and cutting, or the formation of explosive mixture during gas cutting

(2) burns caused by scalding hot metal droplets or tempering, and diving sickness or suffocation caused by burning air supply pipes, diving suits and other diving equipment

(3) electric shock caused by insulation damage, electric leakage or direct contact with electrified bodies such as electrodes, or secondary drowning accidents caused by electric shock spasm.

(4) mechanical casualties such as crushing, crushing, bumping and smashing occur when objects strike underwater structures and objects collapse and fall

(5) other unsafe factors such as drowning caused by wind and waves that are lighter and more effective than invar tools

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