A decade ago, Smith Brothers formed an exclusive partnership with Isotubi, becoming the sole supplier of their stainless-steel press-fit system. Since then, the system has become an essential part of the SBS product range, valued for its size range and approvals (gas & potable water), which spans from 15mm to extra-large sizes up to 168.3mm (6” inch).
What is Isotubi?
Isotubi S.L. is a Spanish manufacturer specialising in stainless-steel piping systems for plumbing, HVAC, and industrial applications. Founded in 1976 and part of the Grupo Lapuente, Isotubi is recognised for its high-quality welded stainless-steel solutions, which provide exceptional durability, corrosion resistance, all with easy installation via a heat free press-fit connection.
The NUMPRESS System
The Isotubi NUMEPRESS is a 316L Stainless Steel press system with size range from 15mm to 168.3mm. Designed for strength and reliability, the system operates at a maximum pressure of 16 bar, carries a 25-year warranty, and meets BSI Kitemark, WRAS, EN10217-7, & EN10312 certification standards. Smith Brothers also stock 304 stainless tube for customers which require a more cost competitive thinner wall option.
What is Press-Fit?
Fundamentally, the system consists of a fitting, an O-ring, and the pipe. The O-ring is located at the end of a fitting and ensures a secure seal. Once the pipe is inserted into the fitting, the joint is achieved through a press-fit tool that will join the three parts together. The strength of the connection comes from the shaping of the fitting and the pipe.
To ensure durability and performance under high temperatures and pressures, the thickness of the fittings increases in proportion to the pipe size.
| Thickness of fitting (mm) | Diameters (mm) |
| 1.5 | 15, 18, 22, 28, 35, 42, 54 |
| 2 | 76.1, 88.9, 108, 139.7, 168.3 |
| 2.6 | 139.7, 168.3 |
O-ring options
There are four different O-rings available, which will need to be applied to different applications, including:
| Type | Colour | Description | Applications | Temperature | Pressure |
| EPDM | Black | Ethylene rubber, resistant to ageing and hot water | Potable water Cooling Fire protection Oil-free compressed air | -20ºC to +110ºC | Up to 16 bar |
| FKM | Green | Fluorinated rubber | Oils Most hydrocarbons Solar installations Compressed air (Class 5 or higher) | -20ºC to +200ºC
| Up to 16 bar |
| FKM | Red | Fluorinated rubber | Saturated steam | -10ºC to +160ºC (up to 170ºC peaks) | Up to 7 bar |
| HNBR | Yellow | Nitrile rubber | Gas | -20ºC to +70ºC | Up to 5 bar |
The Benefits
As an M-profile press-fit system, it offers multiple benefits, including:
- Time and money saving – The press fit method takes less time to assemble compared to traditional methods, meaning that labour costs and assembly time are reduced.
- Pre-Fabrication potential – components can be pre-assembled, making installation in confined spaces simpler and faster.
- A safer method of installation – no hot work permit is required, reducing the risk of accidents, injuries and fire hazards.
- Cleaner installation – no lubricating oils are needed, keeping installations and work areas clean.
- Hygienic and environmentally friendly – stainless steel offers strong resistance to oxidation and deformation at high temperatures, supporting long-term performance.
- XL sizes – the system can be available in XL sizes, both 5” (139.7mm) and 6” (168.3mm) for both water and gas. More information available here.
- Minimal pressure loss – the system design supports efficient flow rates through the installation.
- Building Information Modelling (BIM) – Isotubi provides BIM files to support the design and coordination of projects across architecture, engineering, and construction teams. Integrating BIM reduces waste, minimises rework and enhances on-site productivity, leading to more efficient and cost-effective builds. BIM services and files available here.
Case Studies
Isotubi has been successfully installed in numerous projects, including:
Training
As an exclusive distributor, Smith Brothers offers specialist training and technical support through its regional product specialists available in person or via Microsoft Teams. Upon completion of training, participants receive a certificate and an ID card, confirming that they have successfully undertaken the training and have activated the system’s 25-year warranty.
For more information or to book training, please contact your local Product Specialist by clicking this link and completing the contact form on the page.
Nationwide Availability and Online Ordering
Isotubi can be purchased nationwide at any of the Smith Brothers branches, and available to order online for same-day collection or next-day delivery through the customer portal at: https://sbsonline.net/isotubi. The portal provides real-time stock updates and access to technical documentation to support project compliance.
NEED HELP WITH PIPE SUPPORT?
Smith Brothers can also support your Isotubi installation with a complete range of pipe support solutions, including bracketry, clips, channel, fixings and associated accessories. Whether you are working on a plantroom, riser, corridor module or full mechanical installation, our teams can help you source the right pipe support to complement any pipework installation. This means you can keep more of the package under one roof, reducing the need to source pipework from one supplier and support systems from another. For contractors who may usually look to specialist bracketry suppliers, Smith Brothers offers a practical alternative for all your pipe support needs supported with the same technical support such as load test data, expansion design service and excellent stock levels both locally and nationally.
