Plugs, Retractables, Access Fittings
Plugs, retractables, and access fittings are the most common types of equipment available for pipeline internal corrosion monitoring. While plugs are the least versatile of the equipment options, there are advantages and disadvantages to each type of equipment.
Plug (hex or bull plug) coupon holders are the least expensive option when it comes to pipeline internal corrosion monitoring. While the economics of plug coupon holders can be appealing, there can be limitations to their effective use in pipeline internal corrosion monitoring. Plug coupon holders will require isolation and depressurization prior to insertion or removal. Dependent on the location chosen, this may involve significant releases from the pipeline. It may also be difficult to place the coupon in the same position within the pipeline on subsequent removals. That said, plug coupon holders remain a common equipment type as they can be installed on existing 1” or 2” weld-o-lets.
Retractable coupon holders are a versatile alternative to plug coupon holders. Retractable coupon holders can be inserted through existing 1” weld-o-lets, and require the installation of a full port 1” valve. The advantage over plug coupon holders is that retractable coupon holders can be pulled without isolation and depressurization of the pipeline, resulting in no down time and minimal release due to depressurization of the equipment only. Retractable coupon holders also allow the weight-loss corrosion coupon to be placed in the bottom of the pipeline via top of the line access. Flush mount attachments can also be utilized on retractable coupon holders to enable pipe wall corrosion monitoring (clearance permitting).
RYSCO Corrosion Services is pleased to provide our own solution for retractable coupon holders. This in-house solution (full CRN, AQP certifications) for retractable coupon mounting provides all of the advantages of the above, with special provisions for small diameter valve installations. Models for online sampling are also available. For more information, please review the data sheet here.
Access fittings are available in many mounting configurations and are a suitable alternative to retractable and plug coupon holders. Primary advantages to access fittings are the ability to place monitoring in exactly the same position in subsequent pulls, the easy exchange of weight-loss corrosion coupons for electronic monitoring, and the ability to retrieve the monitoring equipment without isolation and minimal pipeline depressurization from the equipment. Access fittings are available in many mounting configurations (flanged, butt weld, flare weld) and various metallurgies. A significant advantage to access fittings over retractable and plug coupon holders is the ability to collect produced water samples while the pipeline remains online.
If you are interested in learning more about this service, please contact us.
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