So This Is Christmas

Merry Christmas is such an infectious feeling I like to feel that way all year around.

So if you are visiting just before Christmas, just after Christmas or even here on Christmas day I am sure you will find something of interest for you and in the spirit of Christmas.

It may be said that Christmas is no longer a celebration but this must be spoken by people that have never had trouble closing their eyes on Christmas Eve in an expectation of what maybe left for them on the carpet under the tree.

I continue to look forward to the surprise on my Grandchild's faces to this day at Christmas events.

Merry Christmas - Merry Christmas - Merry Christmas

Saturday, November 22, 2008

The Pros and Cons of Underwater Welding Techniques

By Sammy L Droste

Underwater welding is an important part of any industry where structures are underwater, or shipping is involved. It doesn't matter whether the structure is a fully submerged pipeline, a partially underwater platform, or a ship. Metal structures need to be repaired, and not all of them can be removed from the water.

Developing good technology for underwater welding is important. Ideally, an underwater weld ought to be strong enough to permanently be part of the structure. It should also be quick and cheap to implement, without being dangerous - unfortunately, no method can meet all of these standards.

There are a number of risks involved in most underwater welding, so it needs to be done carefully, by specialists who know what they're doing. Underwater welders are in demand in many industries, including shipping, oil and gas, and even military operations.

Wet and dry underwater welding are the two basic types. Wet welding is when the weld is exposed to the water while being created. It's a speedy, inexpensive welding method, and it's commonly used on underwater structures, or when a ship can't be put into dry dock.

The down side of wet underwater welding is that it's not as structurally stable as a dry weld. Water can interrupt the welding process, cause hot and cold spots, or even explosive pockets of hydrogen and oxygen. Wet welds are almost always temporary, and don't provide as great percentages of elongation as dry welds.

Wet underwater welds need to be repaired more frequently and require routine inspections for damage. This is an alternative to putting a ship into dry dock before scheduled, but in the long run, it's not always the cheapest.

Dry underwater welding may also be called hyperbaric welding. Usually, it's done inside a chamber made to isolate the weld from water - this chamber is often pressurized, and contains inert gas. The chamber can be big enough to hold all the equipment, plus the welder, or so small they only surround the weld.

One variant of dry underwater welding developed by Neptune Marine uses a small chamber filled with inert gas. This gas is pressurized to one unit above the outside water pressure, which prevents contamination. The small chamber can be easily and quickly built, which is why this is one of the least expensive forms of dry underwater welding.

Dry welding is generally considered to be time consuming and expensive, which is why it's not usually used for quick repairs or fixes that need to be done without disrupting normal routines.

Underwater welding has a number of risks associated with it. One of them is shock from improperly insulated or used equipment. Another is decompression sickness, a problem that can be avoided with the right precautions, but which can be lethal if they're not observed.

Every kind of welding has its own problems and benefits. Picking the right method for your application requires knowing your available resources and your needs. Be sure to investigate all options, even if they're new to the market, when you look for the perfect underwater welding solution.

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