CRACK REMOVAL INVOLVING ENGINEERED PRESSURE ENCLOSURE & HOT TAPPING
Problem
Customer has requested removal of a ~30mm long crack on the circumferential portion of their pipeline. The crack originates from a pipe shoe weld on the NPS 24 X 7.92mm WT Produced Emulsion line. Customer is looking to complete this removal if possible without a complete line shutdown and drain of product.
Utilization of services to Correct the problem
To save a complete shutdown on a several Kilometer long pipeline flowing produced Emulsion at a rate of 0.5M3 per second we were tasked with completing an
Online service solution. Utilizing our experience with our Engineered Pressure Enclosures and Hot tapping a plan was devised to enclose the leak and weld a hot tap fitting around it. Learn more about our full-suite Engineering & Testing capabilities.
This would allow us to remove the crack and continue to allow the owner to operate the pipeline at full capacity.
Our first hurdle to tackle was the high slugging loads in the header, which resulted in the line needing to be secured with an additional structure prior to cutting and removal of the pipe shoe associated with the crack.
Figure 1
Leaking Crack Extending from Shoe Weld
A dummy pipe was prefabricated with a new shoe and was welded to the blind flange at the end of the run. As this line was still live In-service welding techniques and NDT practices were utilized. Discover our comprehensive Non‑Destructive Testing Services that ensured weld integrity throughout live-line operations.
The dummy pipe and shoe was supported by a newly installed screw piles and structural steel located just downstream of the crack.
Figure 2
Additional support structure added to existing flange downstream of crack
Removal of the existing shoe that was associated with the crack was vital to allow us to create a custom leak enclosure and contain the crack to prevent product from entering the welding area.
The weld associated with the crack was to remain undisturbed, along with a tab of shoe material ~1in tall and the length of the weld as shown in Figure 3.
Figure 3
Tab of Shoe Material to Remain
Once this was accomplished this allowed us to install the temporary leak isolation cup over the crack and tab as shown in Figure 4 Utilizing a fast-curing sealant compound we created a seal around the cup to allow for the welding to be accomplished online without product coming in contact with the welding.
Figure 4
Leak Isolation Cup
Installation of the 6” weldolet using Inservice welding procedures prevented a complete line shutdown. Due to the nature of the crack a reduced pressure test was recmonded to prevent opening up the crack further and spreading it.
This paired with a completion weld designation resulting in higher levels of inspection at each step of the welding phase were utilized to prevent a weld failure on the hot tap fitting. We offset the location of the weldolet to allow us to drill into the parent material and remove the crack undisturbed by the drilling method.
Figure 5
Hot Tap Fitting Installed
Prior to hot tapping we removed the engineered pressure enclosure once the hot tap valve was installed before hot tap machine was installed. We completed the tap and removed the crack intact allowing the client to do further analysis on the issue. Post hot tap we installed a completion plug and left the fitting with a double block and bleed system at this point for the client’s future use.
Utilizing the combined functions of the Leak repair service line and Hot Tap services we successfully completed a removal of the crack for analysis and to prevent it from propagating further. Explore our full range of Specialty Services, including hot tapping, line stops, custom enclosures, and more.
The successful utilization of these combined methods allowed the customer to run the line at full capacity throughout the work scope with no loss in production, allowing approximately 80,000 BBL of production to continue unhindered.