Burn, Baby: The Beautiful World of Underwater Cutting

…a time to tear down and a time to build (Ecclesiastes 3:3)

Underwater CuttingMost jobs have two sides to them – destruction and creation.

If you’ve worked in the construction industry, you know this to be true. On any given day, materials must be cut, shaped, welded, soldered and scrapped.

Bigger jobs require bigger tools, but the end result is the same.

Underwater welding jobs are what many commercial divers are known for, though they may be few and far in between.

A 3,000-foot pipeline pumping 24 hours a day can’t simply stop because of a small leak for a “cut and replace” session. Welder-divers and their team have to work around these issues and brainstorm ways to repair safely and securely. Some processes necessitate extreme delicacy.

But burning is equally important.

In general, underwater welders burn (cut) more than they weld. As maritime companies continue to push the envelope with new advances in products and technology, they must throw the old away and start afresh.

Welder-divers are perfect for these jobs, and they make careful preparations before slicing and dicing.

Constituting the Perfect Cut: Underwater Burning Processes

Most burning processes work similarly to top-side welding, but underwater welders concerns with safety and reliability are heightened in their environment. In addition, the burning equipment creates bulk and decreases mobility.

  • Flame – Simple and straightforward. It works similarly to a welding torch but has an extra pipe for oxygen blasts to clear away debris.
  • Plasma Arc – Combining inert gas and electricity, divers sometimes use computers to control the cutting process. It’s extremely clean when finished.
  • Explosion – Although rarely used, explosion cutting has its place when breaking down thick, non-volatile barriers. Divers pack specially shaped charges into the cavity to create a focused shockwave.
  • Water Jet – These specially designed jets focus hundreds of pounds of pressure on a single point, cutting through tough materials as strong as titanium.
  • Mechanical cutting – A general term for other types of cutting that use blades, saws and other tools to slice through material.

A mechanical method called “diamond wire saw” cutting was also developed to increase the efficiency and accuracy underwater.

It has proven to work quite well especially with pipeline cutting. Most of these machines have plenty of flexibility to allow them to cover the smallest to largest radius pipelines. Diamond wire saw cutting would be categorized under mechanical cutting, but I thought its high value was worth mentioning separately.

Here’s a visual simulation that was created by one an underwater construction company. They use a complex device that latches onto the pipeline and makes angled incisions to cut it.

[responsive_video type=’vimeo’]https://vimeo.com/57854168[/responsive_video]

 

To Burn, or to Weld: One Question with Multiple Answers

Everyday, underwater welders make hundreds of decisions for projects.

One of the biggest decisions determines whether cutting, welding or a combination will provide the best result. Sometimes the answer is obvious, such as a hairline crack in a ship’s hull that needs welded. Other times, underwater welders weigh the pros and cons according to the job. In general, here are the benefits.

  1. Requires less time
  2. Often machine operated
  3. Clears debris for fresh material

In the end, remember that burning and welding underwater are both required for certification and a successful diving career.

You can’t have one without the other. But don’t be surprised if burning fires you up more than welding – we’re all naturally born pyromaniacs anyway. Just be glad you’re burning in the water.

Updated: April 27, 2017 — 3:24 pm