Commercial diving

Commercial diving is a job that most people are not familiar with so I thought I would take this opportunity to talk about and share what is actually going on in this video and hopefully spark some conversation about this incredible job and the men and women that do it for a living.

This is an offshore job, the diver is “dressed” with safety checks on the surface and then rides in a basket called a LARS (launch and recovery system) until they are at the working depth of the job (air divers can go down to 50m).

This job is to place a sleeve/ patch or clamp known as a PLIDCO over an area of pipe identified thinner than desired so we have to excavate to get access to the entire circumference of the pipe.

To excavate we use an air lift that sucks up the loose material until we his “cap rock” a concretion layer with varying degrees of hardness. We use a jackhammer to cut blocks each side of the pipe before we then break through at the 6 o’clock position of the pipe from left to right.

When our hole is on depth we then use a 10,000 psi (690 bar) water jet to cut through the cement “weight coat” (the protective coating on the pipe) to expose the bare metal. If the pipe has a welded seam that must be ground back where the sealing face of the PLIDCO will sit.

Once the pipe is ready, the location is determined, it is then time to land the two halves of the PLIDCO. This comes with its own set of steps and risks because it is attached to the crane on the vessel above which is at the mercy of the sea in terms of swell ( vertical up and down movements). If you can imagine the as the vessel goes up so does the crane and whatever is attached on the wire, and then as it comes down, if not timed right can result in damage to the pipe the PLIDCO and worse case the diver. So it’s important to know what you’re doing and to time it correctly as shown in this video (light sea state).

When the clamp is on the pipe the it needs to be rotated 90°, with a small clamp this can be done by hand but with a larger clamper it would be done with the crane.

Then the bolts will be fitted, and set the gap between each half of the clamp to around 2-3mm. Then the check valves and their caps will go on.

You will see the welding of a threaded bolt. This bolt is to ensure a metal to metal contact so that the clamp and the pipe are protected with the anodes that are attached to the clamp. The welding is to ensure that the bolt can’t move breaking that connection.

Finally the video inspection of how the clamp is left.


If you have any questions please leave them in the comments section below. Thank you for watching.