Hot Stabs

What is a Hot Stab?

Hot Stabs are specialized connectors used in subsea energy operations to facilitate the transfer of hydraulic fluids, chemicals, and electrical signals between subsea equipment.

The Hot Stab is based upon a section of mandrel being inserted in a receptacle with matching ports, allowing pressurisation of fluid between the two isolated sections separated by seals

These connectors are designed to be reliable and robust in harsh underwater environments, ensuring the efficient operation of subsea systems.

Here is an overview of Hot Stabs by Secc:

1. Hydraulic Hot Stabs: Used for the transfer of hydraulic fluids to control subsea valves, connectors, actuators, clamps and pumps.(list is not exhaustive) 
2. Chemical Injection Hot Stabs: Designed for the injection of chemicals such as methanol to prevent hydrate formation.
3. Electrical Hot Stabs: Facilitate the transfer of electrical power and signals between subsea systems.
4. Multifunction Hot Stabs: Combine hydraulic, chemical, and electrical connections into a single unit.

Image: API 17H/ISO 13628-8 TYPE 2 HOT STAB – 20,000 PSI

Components and design (Hydraulic Hot Stabs) 

1. Stab Plate: A stationary component mounted on subsea structures like christmas tree, manifold, or subsea distribution unit.
2. Receptacle: A stationary component that receives and secures the Hot Stab, aligning the fluid ports.
3. Stab: The mobile component that mates with the Receptacle. It is often manipulated by a remotely operated vehicle (ROV) or diver.
4. Seals: High-integrity seals to prevent leakage and ensure a secure connection under high pressure and harsh conditions. The seals are often pressure balanced removing separation forces. 
5. Alignment Features: Guide Nose, Funnel, Bucket and Latches and Alignment aids to ensure accurate mating of the Hot Stab and Receptacle.
6. Ports: The Hot Stab is attached to flexible hose/s. Which transfer the fluid. Depending on the function multiple Ports and Hoses can be integrated. 
7. Handle: The Handle allows the ROV or Diver to secure, manipulate and move the Stab 
8. Hoses: Flexible hoses transfer the fluid between the Stab and the ROV or device. 

Hot Stab terms 

• Live: A Hot Stab and Receptacle that has 1 or more ports and is used for pressurized fluid transfer. 
• Blind: A Hot Stab that does not have any ports and does not transfer fluid but seals and blocks the receptacle under working pressure. 
• Dummy / Parking / Plug: A Stab and/or Receptacle that retains the Stab when not in use and/or prevents debris or marine growth building up in the Receptacle. 
• Single / Dual / Quad / Multi: Refers to the number of ports. 
• Type: API/ISO reference to category and design of Hot Stab and Receptacle. 
• HIGHFLOW: Secc angled full bore Hot Stabs and Couplings. 
• MAXFLOW: Secc straight  full bore Hot Stabs and Couplings. 

Flow or Static Hot Stabs

Subsea systems consist of a range of components and devices to suit the task. Static operations may require low to medium flow rates for a short period to operate a Connector, Valve or Clamp from one position to another. Whereas Pumps and Flow-Lines may need medium or high flow for continuous flow. 

Secc produces a range of standard and patented Hot Stabs suiting a variety of flow and control requirements. 

Traditional Valve technology can be incorporated into Hot Stabs and Receptacles to prevent spill during connecting and disconnecting. Such as Check Valves/Non-Return Valves (NRV’S). This protects the environment against unwanted spills and prevents sea water ingress into hydraulic systems. This is particularly advantageous for operations seeing high frequencies of connections and disconnections. The Type-1 ECOFLOW is the ideal solution for static operations. Whereas the ECOFLOW+ offers HIGHFLOW unobstructed flow for continuous flow applications, utilizing Secc’s patent technology. 

Types of hydraulic Hot Stabs

Hot Stab sizing

The “size” of a stab can be dictated by the task, type or interface requirements. API/ISO Hot Stabs are interchangeable if the API/ISO-TYPE, size and port spec match. It is important to know what the Hot Stab is being integrated into. For new builds a wide selection of Hot Stabs are available and can be integrated into the clients system by configuring the interfaces such as mounting brackets, port spec and handle requirements.  

When referring to the size of the Hot Stab. The fluid Ports and Receptacle ID are common starting points. It’s key to understand what’s what when determining the best and correct Hot Stab solution. API/ISO often references the receptacle ID when quoting the size. I.e a 45mm TYPE Hot Stab has a 45mm Receptacle bore but 3.2mm fluid port/s. Whereas MAXFLOW and HIGHFLOW Hot Stabs refer to the actual fluid port ID. I.e a 1” MAXFLOW/HIGHFLOW Hot Stab has a 3” receptacle bore and a 1” fluid Port. 

Secc’s Technical sales team are at hand to support the selection process. sales@secc-oilandgas.com

Hot Stab applications

• Subsea Control Systems: Hot Stabs can connect hydraulic power units to subsea control modules to operate valves, actuators, clamps and Bend Restrictor Couplings (BSC).
• Sampling and diagnostics: Hot Stabs can be used to test seals and connections and take fluid samples. 
• Chemical Injection Systems: Hot Stabs can deliver chemicals to prevent hydrate formation and corrosion in subsea pipelines.
• Intervention and Workover Operations: Hot Stabs can provide temporary connections during maintenance and repair activities.
• ROV Operations: Hot Stabs allow ROVs to connect and disconnect hydraulic and electrical systems for intervention tasks.
• Decommissioning:  Hot Stabs hydraulic power to subsea decommissioning tools and valved for zero spill and zero water ingress for the hydraulic circuit.
• Trenching: Hot Stabs hydraulic power to subsea Trenching tools and valved for zero spill and zero water ingress for the hydraulic circuit.

Hot Stab key features

• Reliability: Hot Stabs are engineered to operate reliably in extreme subsea conditions, including high pressures, low temperatures, and corrosive environments. This reliability is tested and quantified in accordance with API/ISO and internal test programs. 
• Modularity: Hot Stabs are available in various sizes and configurations to suit different applications and equipment specifications.
• Ease of Use: Hot Stabs are designed for quick and efficient connection and disconnection by ROVs and/or divers.
• Safety: Hot Stabs incorporate safety features to prevent accidental disconnection and ensure secure operation.

Hot Stab maintenance and handling

• Regular Inspection: Routine checks for wear and tear, especially on seals and alignment features, to ensure continued reliability.
• Correct Storage: Store in a clean, dry environment to prevent contamination and damage.
• Training: Operators should be trained in the proper use and maintenance of Hot Stabs to ensure safety and efficiency.

Hot Stab advantages

• Reduced Downtime: Hot Stabs enable quick and efficient connection and disconnection, minimizing operational downtime.
• Versatility: Hot Stabs are suitable for a wide range of subsea applications, enhancing operational flexibility.
• Enhanced Safety: The robust controlled design of Hot Stabs and secure connections improve safety for personnel and equipment.

• Environmental Conditions: Hot Stabs must withstand harsh subsea conditions, including high pressures and corrosive elements.
• Alignment: Hot Stabs ensure precise alignment during connection to avoid damage and ensure a secure fit.
• Maintenance: Hot Stabs should undergo regular maintenance is critical to prevent failures and ensure long-term reliability.

Hot Stabs are crucial for the efficiency and safety of subsea oil and gas operations, providing reliable connections for the transfer of fluids and signals under challenging underwater conditions. Secc has more than 15 years experience in the design, development, manufacture and deployment of Hot Stabs to the biggest operators around the globe.

Secc Hot Stab products and services

Hot Stabs and Receptacles: API, ISO, MAXFLOW, HIGHFLOW, ECOFLOW and non standard solutions

Hot Stab Spares: Secc stock a variety of Seals, Handles and other items for Hot Stab systems.

Panels and Systems: Hot Stabs assemblies can be supplied complete on fully built and tested Panels.

Enquiries

For more information on standard and project specific Hot Stabs please contact our sales team:

Hot Stab Specifications

API 17H:
Published by the American Petroleum Institute, it is the U.S. standard for Remotely Operated Vehicle (ROV) interfaces on subsea production systems. It incorporates many of the guidelines originally set out in ISO 13628-8.

ISO 13628-8:
An international standard developed by the International Organization for Standardization (ISO), covering the same topic as API 17H.

The designation API 17H / ISO 13628-8 refers to the fact that these two standards are closely aligned and often treated as equivalent in many respects.

API 17H and ISO 13628-8 were developed in parallel to ensure compatibility between the standards. This alignment allows manufacturers and operators to design equipment that meets both standards, facilitating interchangeability and global acceptance.

Both standards specify requirements for ROV interfaces, including hot stabs, torque tools, and other subsea equipment interfaces.

They ensure equipment designed to one standard will typically meet the requirements of the other.

API 17H includes some additional requirements and considerations that are specific to U.S. practices and environments, such as Gulf of Mexico operations.

ISO 13628-8 may be more widely recognized and required for projects outside North America, especially in regions where ISO compliance is mandatory.

ISO 13628-8 has been superseded by newer editions of API 17H, for new build Hot Stabs, which fully integrates the relevant ISO content. Most operators now reference API 17H as the prevailing standard, but the core principles remain the same.

Implications for Equipment Design and Compatibility

For international projects, checking whether ISO compliance is explicitly required is important.

Equipment designed to API 17H should also comply with ISO 13628-8 (and vice versa), provided there are no project-specific deviations.

Global use: API 17H is now considered the standard for most subsea projects worldwide, even in regions that previously required ISO standards.

For further information and support contact Secc’s sales team.