Beyond the Design Pressure: External Loads on Leak Sealing Enclosures

The design of a leak sealing enclosure begins with two parameters: design pressure and design temperature. Shell and element thickness, bolt size and the sealing arrangement follow from them. This part of the design is well defined by the construction codes and is seldom the source of difficulty in service.

A Temporary Leak Sealing Device (TLSD), also referred to as an engineered mechanical enclosure or clamp, is a purpose-designed enclosure secured around a pipe or component to provide pressure containment and leak control while the system remains in operation. Unlike new equipment, it is installed onto a system that is already loaded, onto a component whose condition is degraded, and it commonly remains in service for years.

Two distinct load sets therefore govern its performance. The first arises from the pressure boundary and from the installation itself, and is generally identified and designed for. The second is transmitted from the piping system and the environment across the installed life, and is where design bases are most frequently incomplete. This article summarises the first and examines the second in detail.

Material Compatibility for Sour Service Assets Operating at Low Design Temperatures

Pressure equipment operating in wet H₂S environments at low temperatures are subjected to engineering challenges. The challenges are Hydrogen-Induced Cracking (HIC) and Sulphide Stress Cracking (SSC) brought about by the wet H₂S. Another challenge is the low-temperature of below -29 °C, which represents the critical material-ductility threshold under ASME, creating potential for Low Temperature Brittle Fracture.

In the application of a Temporary Leak Sealing Device (TLSD), wet H₂S environment is formed due to the nature of the cavity created around the leak. This wet H₂S environment combined with a low-temperature environment creates a combined integrity challenge engineers must solve through the first-principle mechanical and code-driven verification as well as strict material choices.

Engineers must establish a validation for TLSD for this environment using repair code conditions explicitly to ASME Section VIII Division 1 and NACE MR0175/ISO 15156. This validation should cover the nature of brittle fracture in Carbon steels due to low temperature and the hydrogen diffusion due to the wet H₂S environment. This technical write-up will cover the aspect of the ASME and NACE that dictate material choice and testing with specific focus on SA-516 Gr70 Normalised plate and SA-320 L7M bolts.

Time-Critical Engineering Managing Projects with Near-Zero Float in Online Leak Sealing

Online leak sealing projects operate in one of the most time-sensitive environments within industrial maintenance. Unlike conventional engineering projects – where planning and execution may span weeks or months -leak sealing interventions are often required within hours to prevent production losses, safety incidents, and environmental impacts.

This creates a project environment characterised by near zero float, where delays in any single activity directly impact the outcome of the overall project. In such conditions, traditional sequential project execution is not feasible. Success depends on the ability to manage tightly coupled activities with speed, technical accuracy, and cross-functional coordination.

This article explores how time-critical engineering principles – specifically critical path management and parallel workflows – are applied in online leak sealing projects, illustrated through a real project involving a 50-inch steam and condensate flange weld leak in South Africa.

Design Life of On-Line Leak Sealing Enclosures

On-line leak sealing enclosures are widely used in the oil and gas, petrochemical, power generation, and process industries as a means of sealing and repairing leaks on pressurized piping systems and pressure-containing components without requiring an immediate shutdown.

These devices are defined as engineered mechanical enclosures or assemblies designed to contain leakage while the equipment remains in service. The sealing mechanism of these enclosures typically utilise compression based or injectable sealing elements.

Although these repairs are often necessary to maintain production continuity and manage short-term operational risk, the question of how long such a device may safely remain in service is one of the most important engineering considerations associated with their use. Their safe use depends on a clear understanding of the remaining condition of the affected component, the expected rate of future deterioration, and the operating limitations of the surrounding system.

Navigating Health and Safety for Leak Sealing

In pressurised systems, a leak is not simply a maintenance defect but rather a loss of pressure boundary integrity and a potential uncontrolled release of energy. That energy may present as high-temperature steam, stored mechanical pressure, or hazardous chemical exposure. Regardless of the service, a leak immediately increases risk to personnel, assets, and operations. Temporary leak sealing must therefore be treated as a health and safety intervention, not just a quick repair. A Temporary Leak Sealing Device (TLSD) is intended to bring the system to normal operating conditions and provide containment long enough for a permanent repair to be planned and executed during the next plant shutdown or first available opportunity.

At Beruseal our online leak sealing is executed as a controlled, health and safety driven solution, not an improvised best effort attempt.

Designing Sealing Systems for Uncharacterized Leaks

In live industrial environments, leaks rarely present themselves as textbook defects. They occur on insulated lines, old repair welds, around legacy clamps, and on pipelines that have seen years of service changes and undocumented work.

In this context, we often face what can be called an uncharacterised leak, which is a defect where one or more of the following is only partly known:

• Defect geometry
• Process medium / service
• Temperature
• Pressure
• Access and landing areas for an enclosure

A clamp refers to a purpose-designed enclosure that is bolted or otherwise secured around a pipe or component to provide pressure containment and/or leak control.

Uncharacterised leaks are especially common on brownfield facilities, which refers to existing plants that have been in operation for a long period, as opposed to newly built “greenfield” sites, refineries, and long-term pipeline system, where drawings don’t match reality and where existing clamps have effectively become part of the pipeline. When older clamps start leaking, they bring irregular shapes and surfaces, and unknown load paths into the equation.

This article looks at how Beruseal approaches these situations from a mechanical engineering perspective, treating every Temporary Leak Sealing Device (TLSD) as a small pressure-retaining enclosure, designed and verified using recognised vessel principles, even when the defect itself is not well defined.

The Safe Design and Construction of Mechanical Leak Sealing Enclosures

The nature and function of an on-line leak sealing device (OLSD) require these enclosures to be scoped, designed, manufactured, and installed within a very short timeframe. Such installations are typically performed under extremely hazardous conditions. Despite this urgency, the foremost priority in any reactive maintenance activity involving pressure-containing equipment must always be the safety of the personnel performing the work.

Given the operational pressures and the inherent hazards associated with OLSD installations, it is of utmost importance that each device is designed and manufactured to ensure safe installation and reliable operation.

Because time is often a critical factor in repairing a pressurized leak using an OLSD, there is significant pressure to supply the required components and equipment as quickly as possible. Adhering to established safety procedures, repair specifications, and recognized construction codes throughout the process is imperative to protect installation personnel and to ensure the overall feasibility and integrity of the repair.

Composite Wrap Repair vs. Online Leak Sealing

In industries such as oil and gas pipelines, chemical processing, and power generation, maintaining the integrity of pressure components (pipes, vessels, etc.) is crucial. When defects or leaks occur, operators have two broad non-intrusive repair options: composite wrap repairs and temporary online leak sealing . Composite wrap repairs involve wrapping the damaged area with fibre reinforced polymer composites to restore strength, whereas temporary online leak sealing uses Temporary Leak Sealing Devices (TLSD) and injectable compound sealant to stop active leaks without shutdown. This report provides a technical comparison of these methods, focusing on their mechanisms, code compliance (ISO 24817, ASME PCC 2, ASME BPVC Section VIII), safety, cost-effectiveness , scope, and limitations.

Oil and Gas Insurance: The Strategic Edge of Temporary Leak Sealing Devices

In the oil and gas industry, downtime refers to any period when piping and vessel systems of oil, gas, or other fluids is interrupted due to planned maintenance, unexpected failures, or emergencies such as leaks. The impact of these interruptions is downtime, which creates limited capacity or a complete shutdown of line operations. Downtime is especially critical because these pipelines often operate as the backbone of larger supply chains, meaning that even a short shutdown could have effects across multiple industries. The causes of downtime can range from scheduled inspections and component replacements to unexpected events such as equipment malfunctions, failure and uncontrolled release of product.

The Lifecycle of a Temporary Leak-Sealing Device: From Design to Deployment

Keeping a refinery or petrochemical plant on-line when a pressurized line starts to leak is a race against time and lost production. Temporary leak-sealing devices are engineered enclosures that bolt over the leaking defect, restoring full pressure containment, often giving operators years of breathing space until the next planned shutdown or next scheduled maintenance. What follows is a walk-through of the complete project lifecycle so you can see exactly how a clamp moves from the first site survey to safe, monitored service, and the impact of each of these stages.