Engineered Touchpoint Access refers to the controlled process of lifting a pipe to access the touchpoints between the pipe and its supports where corrosion often develops, a mechanism often referred to as Corrosion Under Pipe Supports (CUPS).
Engineered Touchpoint Access allows for a wide range of remediation techniques to be applied directly to the touchpoints to prevent further damage and extend the lifespan of pipelines. Without lifting pipes away from their supports, these areas are difficult to access and inspect, leading to undetected corrosion and potential failures.
By temporarily lifting the pipe using a pipe rack jack, technicians can conduct various remediation activities, ranging from surface preparation to installing protective materials, all aimed at preventing or mitigating touchpoint corrosion (TPC).
4.1 Surface Preparation (Sandblasting and Cleaning)
Surface preparation is the foundation of any remediation effort and is critical for ensuring the success of subsequent treatments. Sandblasting, or abrasive blasting, is used to remove existing corrosion, dirt, and old coatings that may have accumulated at the touchpoints.
By lifting the pipe off its support, technicians can fully access the corroded areas and clean them down to bare metal. This process ensures a smooth, corrosion-free surface, essential for the adhesion of protective coatings, wraps, or other materials applied afterward. Proper cleaning not only removes current corrosion but also provides a clean slate, enabling more effective protection moving forward.
4.2 Recoating and Corrosion Protection
Recoating is a primary corrosion prevention technique that involves applying a new layer of protective material to the pipe surface after it has been lifted and the surface prepared. The newly exposed pipe can be treated with specialized coatings such as epoxies, polyurethane, or other industrial-grade solutions designed to resist environmental degradation.
The coating acts as a barrier between the pipe and corrosive elements like moisture, chemicals, or oxygen. In environments where pipes are exposed to harsh conditions, such as coastal areas or chemical plants, recoating can significantly extend the life of the pipeline. This remediation is particularly important after removing any prior corrosion through sandblasting, ensuring a fresh, long-lasting protective layer.
4.3 Installation of Wear Pads
Wear pads and pipe shoes are essential for preventing future touchpoint corrosion by physically separating the pipe from the support structure. Once the pipe is lifted, these devices can be installed at the touchpoint to minimize direct metal-to-metal contact, which is one of the leading causes of corrosion.
Wear pads are made from non-corrosive materials, such as polymer composites, and also provide a non-slip surface for the pipe to move across to accommodate thermal expansion, ensuring that the pipe can move slightly without damaging the protective barrier.
Different types of pads exist ranging from generic half-round PTFE pads to flat composite pads to more advanced ribbed pads such as Lift-Off Pipe Supports.
4.3.1 Semi-Circular
The half-round type of pad is great for small bore piping but care must be taken to secure these to the beam correctly. Common methods include screwing them into the beam or gluing them down however screws create new points of ingress for corrosion on the supporting beam and gluing the pads to the support doesn’t hold for very long before failure.
These types of pads also create point loads, and improper sizing can cause them to fail.
4.3.2 Composite Pads
Composite pads have a larger surface area so they are easier to glue down to the support. They also provide a flat surface for the pipe to rest on which eliminates the point load to provide a smooth surface for the pipe to move across. The perimeter of these pads must be properly sealed to prevent water ingress and corrosion of the supporting beam.
4.3.3 Lift-Off Pipe Supports
Lift-Off Pipe Supports are a recent innovation for combating Corrosion Under Pipe Supports (CUPS). They are a more advanced type of barrier consisting of multiple ridges that channel standing water away from the touchpoint while still providing a non-slip surface for the pipe to move across.
Point loading is significantly reduced by using multiple ridges instead of only one and the pads are held in place by tabs that overhang the flanges of the supporting beam making them quick to install without the need for glue or self tapping screws.
Although more costly than other types of pads, these will outlast all other alternatives to provide cost savings in the long run.
4.4 Composite Wrapping and Reinforcement
Composite wrapping is a versatile remediation technique that strengthens damaged areas of the pipeline. After engineered line lifting and surface preparation, technicians apply a composite wrap made of materials like fiberglass or carbon fiber. These wraps, which are impregnated with epoxy resins, act as a shell around the corroded or weakened section, restoring the pipe’s mechanical integrity without the need for replacement.
This method is highly effective for reinforcing pipes that have experienced moderate metal loss due to corrosion, offering a cost-effective solution compared to an unplanned shutdown to perform a section replacement. However, these are considered temporary repairs, designed to extend the service life of the piping until the next planned shutdown when it can be cut out and replaced with a new section of pipe.
4.5 Installation of Mechanical Enclosures (Clamps)
Mechanical enclosures provide immediate and long-term protection for pipes with severe corrosion damage or metal loss caused by Touchpoint Corrosion. They can even be installed on piping with active leaks.
These enclosures, such as clamps or split sleeves, are installed around the pipe once it is lifted from the support, and bolted together to encapsulate the touchpoint to provide containment. In severe cases a strong back system can provide structural reinforcement.
This type of remediation is ideal for cases where full pipe replacement is not feasible or where further corrosion prevention is needed without significant downtime. It is considered a permanent repair although some operators still opt to replace these sections of piping during a turnaround.
4.6 Support Replacement
Corrosion can also occur on supporting beams if they are not properly maintained with protective coatings. If the supporting beams fail, it can overstress the piping and potentially cause leaks.
When a pipe support is damaged beyond repair, all the piping must be lifted to replace the support. Lifting multiple pipes can be challenging, but with Ovolifts' Multi-jacks, multiple pipes can be lifted simultaneously. This is typically done from adjacent supports to avoid obstructions and ensure free access for repairs. This process often requires careful planning and pipe stress analyses to maintain integrity during the lift.
4.7 Pipe Shoe/Saddle Replacement
Pipe shoes come in different shapes and sizes. Some are welded to the pipe while others are clamped on. Welded shoes can cause stress corrosion cracking and clamped shoes can also cause water accumulation and corrosion against the pipping.
Larger piping will typically have a saddle to support the pipe which is essentially a large pipe shoe and these often require a sim plate between the saddle and the support.
These shim plates will also corrode over time and in the process will expand (flake) with tremendous force, applying a vertical displacement against the piping. Sometimes this is acceptable but in some cases the piping forms part of a larger, more rigid structure and if the piping doesn’t have the flexibility to accommodate this vertical displacement then this force translates into significant stress applied to the piping system which can lead to failure.
4.8 Reinstate Displaced Piping
Liquid hammer, especially in large bore piping systems transporting liquids, can be extremely violent. This phenomenon generates high kinetic energy, and an event like an accidental valve closure or flow disturbance can be likened to suddenly stopping a moving train.
The immense energy transfers to the piping system, causing significant line movement, particularly at expansion loops. This movement often leads to longitudinal displacement, and in severe cases, pipe shoes can fall off their supports.
To remediate or repair the pipe means reinstating the pipe shoes onto their supports, the entire section of piping must be lifted simultaneously. While the pipe is elevated, it needs to be pulled horizontally to realign it with its original position on the supports.
This process requires careful coordination and planning to avoid additional stresses on the pipeline and ensure the shoes are correctly repositioned. Proper lifting equipment and engineering analysis are essential to safely carry out this operation and restore the pipeline's support.
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