It is also worth noting that running an IMU tool as part of an in-line inspection (ILI) survey is a relatively modern practice for many pipeline operators. Although there has always been expectations for pipeline contractors to follow design limits for "roping", it has historically been...
Thanks for the reply.
What I have noticed is that most ILI vendors do not report bends with high bend radii or very small bend angles in a typical ILI pipe talley or bending strain report. It is not uncommon for ILI vendors to only report bending strains above 0.2%. "Roped" sections of...
Pipelines are typically constructed using a combination of “roping” (grading the right of way to reduce the number of required factory and field bends) and “bending” (using field bends to accommodate undulations discovered along the right of way during construction).
Roping analysis can be...
I am posting this as a follow-up to the correspondents (above). Please note, I am not posting this to provide owners or contractors with an alternative to meeting the workmanship standards we expect from them (which are typically defined in pipeline codes, regulations, etc.). This is simply a...
Yes we run aluminum gauge plate pig runs after pipeline installation on all pipelines...sized to ~95% ID...same as everybody else...That's how we discovered the ovality issues...
For bigger pipeline projects we also run an ILI caliper tool with nitrogen after backfill...it's better at finding...
As always, I appreciate the reply BigInch.
Of course a contractor is obligated to deliver a defect free pipeline and we do not accept anything less. It is just a hypothetical scenario. There are acceptable ways to evaluate anomalies that can and do exist in pipelines. Where a...
Our buried pipeline specs limit D/t to less than 70 to avoid issues related to use of high D/t Ratio (e.g. flattening, ovality, buckling, increased risk of denting). Use of higher D/t ratio can be approved on a case-by-case basis but for our pipelines, it is rare to come up with a compelling...
I’m curious if anyone here has ever completed an Engineering Assessment (EA) to support a non-conformance to a code requirement during new construction. This is primarily a philosophical question since CSA Z662-15 is unclear regarding whether or not an EA can be adopted at the construction...
We’ve installed lots of fiberglass flowlines that have threaded joint connections but never steel flowlines.
Not sure what location this pipeline is being considered for but in Canada, CSA Z662-15 Clause 4.5.2 limits the use of threaded joints as follows (see below). I assume ASME B31.4/ASME...
How are you planning on crossing this road in your design (e.g. auger bored, jacked, horizontal directional drill (HDD))? How is your pipeline contractor planning on crossing this road during construction? Be careful that the crossing method stipulated in the design and submitted for approval...
Thanks LittleInch.
An interesting argument seems to arise every time I broach this subject (see below). The longitudinal compressive stress formula (referenced above) does not account for any effect of hydrostatic testing on longitudinal thermal stresses.
Consider:
If the pipeline is truly...
When calculating longitudinal compressive stress for restrained portions of pipelines, CSA Z662 references the commonly used formula:
SL = v*SH – E*alpha*(T2-T1)
Where,
SL = longitudinal compression stress
SH = hoop stress due to internal design pressure
v = Poisson’s ratio
T2 = maximum...
Hi LittleInch,
Sorry for the confusion. I am almost certainly misusing the term HDB. By HDB, I mean when we use HDD equipment to drill a level horizontal drill path for the carrier pipe rather than a drill path with a big belly (as we typically would to traverse across a deep river crossing)...
