The water and gas installations in many residential buildings built at the end of the last century is now inexorably approaching the end of its lifespan. Their reconstruction usually has to be done in such a way that it affects the tenants' daily life as little as possible.

This was also the case in a prefabricated apartment building in Prague 6, where the investor demanded the replacement of a deteriorating gas pipe. The essential condition was the super fast execution of this exchange with a fixed time of one day!

This difficult task was undertaken by the experienced company AZ CZ SERVIS s. r. o., which has long specialized in similar reconstruction of apartment buildings and gas pipelines, and has a team of experienced designers and installers who are not afraid of such a demanding project.

For the replacement of the gas pipeline they considered two possible technologies - classic copper piping with press fittings or modern piping made of MERABELL GAS PROFI stainless steel bellows. Preliminary material calculations came out very similar for both materials, although 1 m of copper pipe is cheaper than 1 m of stainless steel pipe. However, the necessity of using many pieces and types of expensive copper fittings made the calculation even.

The main reason why AZ CZ SERVIS s. r. o. decided to use stainless steel bellows was a significant time saving not only in the preparatory work before installation, but above all the speed of the installation itself. It would be very difficult to make an estimate of the number and specification of angles and shapes of individual components for the copper distribution system before demolishing the old distribution system. In practice, this would very likely mean the need to provide specific fittings throughout the day. This could upset an already very tight timetable. This inefficient time is completely eliminated with MERABELL GAS PROFI stainless steel piping. The piping is shaped by hand, which also minimizes the number of joints in the pipeline. In addition, any connection is always a potential danger of a possible gas leak in the future.

Installation procedure

The original steel gas pipe was cut off in the area of the gas meters, however the original vertical route between the floors was retained and used as a buffer. MERABELL DN25 stainless steel pipe was pulled through these pipes and sealed with fire-resistant polyurethane foam to prevent hot air flow in case of fire. Using a T-piece, a tap was made at each node to connect the gas meter. All shaping of the bellows was done by hand, the ends of the pipe were crimped with a lever press. The exposed pipe near the nuts was wrapped with self-vulcanizing tape so that the entire surface of the stainless steel pipe was protected from possible adverse effects. The whole reconstruction took only 3.5 hours.

Technical design

Using the on-line pipe calculator www.merabell.com/calculator, the required pipe dimension DN25 / 5/4" yellow stainless steel pipe MERABELL GAS PROFI with diameter (M00129), 30 meters length was selected. To connect the pipe to the gas meter, 5/4" nuts (M0205) and brass T-pieces (M0237), 5/4"-R1" nipples (M0219) were used.
PANZER fire-resistant polyurethane foam was used to seal the space between the steel and stainless steel pipe.

Features of MERABELL GAS PROFI pipe with protective sheathing

• Certification according to the ČSN EN 15266 standard (Stainless-steel pliable corrugated tubing kits in buildings for gas with an operating pressure of up to 0.5 bar). 
• This EU standard allows the pipe to be routed in a wall without a protector, underground and through a building structure in a protector, when passing through a peripheral wall in a protective pipe. 
• It is made of high quality stainless steel AISI316L (surgical steel). 
• It is flexible and allows shaping by hand. 
• The pipeline is protected by a yellow PE (polyethylene) protective sheathing.
• This product is backed by a superior 10-year warranty.

Project assessment

The replacement of the gas pipeline for a 4-story, 4-unit apartment building and basement was completed in less than 4 hours. The assumption of significant savings in installation time due to the use of stainless steel pipe MERABELL GAS PROFI was confirmed. This fulfilled the investor's requirement for a super-fast one-day reconstruction.

The unlimited lifetime of this distribution system is also a major advantage for apartment owners.