How to Survive a Rig Inspection: Part 5

Mud Systems

In this 16 part series, our head of Rig Inspection Services Steven Lee shares tips on how operators and owners can get through rig inspections with flying colours – and which pitfalls to avoid! Mr Lee has more than a hundred rig inspections under his belt, from all parts of the world. In this chapter, we’re looking at mud systems.

Mud systems are our primary well control system and a vital part of any drilling rig’s safe operations. They cover a variety of equipment in both high and low-pressure systems. It’s always difficult to replicate real operational conditions during rig inspections, commonly due to environmental restrictions imposed upon drilling rigs while they are not on drilling locations.

More often, any testing is limited to the use of circulation of either seawater or, occasionally, fresh water. Full integrated acceptance tests and endurance acceptance tests may allow for high-pressure circulation through chokes or jetting subs. There are two opposing performance criteria for mud systems – high-volume low-pressure supply and low-volume high-pressure supply. Rigs need to be able to meet both.

There are many areas that will be key to rig inspections teams on mud systems, particularly on older units:

  1. Bearing tolerances on mud pumps
  2. Material integrity of high-pressure lines.
  3. Explosive-proof equipment integrity
  4. HVAC systems for pit rooms

An issue with mud systems, commonly identified by inspection teams during reviews of piping thickness, is that no comment has been made on the suitability of the piping for future use. It’s important when you have your third party piping inspections conducted that they identify the original nominal thickness and identify its suitability for future service based on the material type.

Experience has shown that within mud system equipment areas, particularly mud pit rooms and shaker houses, there are often multiple deficiencies to electrical explosion-proof equipment.

As discussed in earlier chapters of this blog, housekeeping and presentation are always key to these areas of a rig. The very nature of mud systems and equipment means that these areas demand a certain level of effort in maintaining them to the highest standards.

Mud Systems Mud Systems

The two photos show two different rigs – one being three years old and having been in constant operations for that entire period. The other is a newbuild in the week of delivery handover. A sharp-eyed and experienced rig inspector will be able to tell which one is in service. Can you?


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