An overview of pipe dimensions
At OMS our business is measuring pipe features - but when we talk about pipe dimensions what do we mean?
As a company that specialises in capturing and analysing key information about our clients’ assets, we spend a great deal of time measuring and inspecting pipes. Although this may seem like a simple task – perhaps involving a tape measure and a can-do attitude – measuring and inspecting pipes accurately is both challenging and essential. Pipelines, particularly those in the oil and gas industry, carry hazardous substances for long distances across difficult terrain or under water. Getting pipe measurements right and fitting them together correctly is vital for pipeline integrity and thus for the safety of the environment and the population.
Separate dimensions each with its own relevance
When we talk about a pipe’s dimensions we mean more than just its length, although this is important. Pipe dimensions include diameter (inside and outside), straightness, end straightness (hooking), wall thickness, machined dimensions, end squareness, bevel dimensions, HiLo and weld profiles. All of these separate dimensions have specific relevance when trying to achieve the level of precision essential for pipeline project success.
Installation and inspection
In this blog we will examine pipe dimensions prior to installation and inspection. If you are interested in those see our website here and our earlier blogs on pipeline and inspection here and here.
Taking care of the details
Although it may seem somewhat dull, a thorough understanding of pipe dimensions is essential for specifying projects correctly. In oil and gas projects taking care of the details is vital – mistakes can cost millions in lost revenue and cause enormous damage to the environment and to corporate reputations.
Specific dimensions
With years of experience of pipe measurement behind us and hundreds of thousands of pipes measured and inspected, at OMS we know that no pipe is completely round, straight or of consistent thickness. Understanding how pipes differ and measuring them to ensure the best possible fit helps oil and gas pipeline projects proceed with more efficiency and a greater chance of success.
Length
A pipe’s length refers to its total length from one end to another post-fabrication but pre-welding and installation. Length is usually measured on a central line through the middle of the pipe.
Pipe length
Straightness
This refers to how much a pipe bends when measured against a straight line.
Pipe straightness
Pipe end straightness (hooking)
Hooking is a feature that particularly affects seamless pipes (created by piercing a steel billet). Excessive hooking makes achieving eventual pipeline alignment extremely challenging.
End hooking
Inside diameter (ID)
Pipes are never truly round on the inside. The thickness of the pipe wall is never consistent and often eccentric – i.e. wall thickness deviations.
Inside diameter
Outside diameter (OD)
Pipes are never truly round on the outside either. OD measurements must be taken from a central point inside the pipe.
Outside diameter
Wall thickness (WT)
This dimension is the difference between the internal and external diameter at each section. Manufacturing methods can cause the WT to vary considerably.
Wall thickness
Machined dimensions
These include taper transition, curvature radius, surface roughness and length of counterbore. They are critical if pipe end machining is used to meet dimensional control requirements, particularly in steel catenary risers (SCRs).
Machined dimensions
End squareness
This refers to how perpendicular the pipe end is when measured against a right-angle.
End squareness
Bevel dimensions
Correctly measuring a pipe’s bevel geometry significantly improves productivity, fit-up and welding.
Bevel dimensions
Internal and external HiLo/misalignment
The internal and external geometry of two pipes brought together for welding.
HiLo/misalignment
Weld root profile dimensions
Measuring these is vital for welded pipes destined for fatigue-sensitive operations and when fabricating pipe with an internal corrosion-resistant alloy (CRA) layer.
Weld root profile
External weld profile dimensions
It is vital to measure these when the external profile must be sanded to achieve the desired specifications
External weld root profile
Considering all these different dimensions, measuring every aspect of a pipe’s internal and external geometry can be complicated and time consuming. Taking the time to do so can mean the difference between project success and failure. In future blogs we will tackle the various measurement methods. If you are interested in finding out more about pipe measurements sign up for our email alerts here.
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Posted 04.02.20
[5 minute read]