What is AC pipe joint and Why Do We Use Them?

Multi-Split Air Conditioner

In buildings with an area of generally 10,000m2 or less, the individual decentralized system has become mainstream over air and water-based systems. This system uses refrigerant, a compound of carbon and fluorine, to efficiently transfer heat by repeating the processes of evaporation and condensation between the outdoor and indoor units, making it easy to switch between cooling and heating.

This individual decentralized system is classified as building multi-split air conditioning or packaged air conditioning. Copper pipes are commonly used in this system.

Building multi-split air conditioning, also known as "building multi" or "building multi-split" is an air conditioning system where a single outdoor unit can individually operate multiple indoor units with different capacities.

For example, in hotels, this system allows each guest room to have customized operation, creating individually comfortable environments. The same applies to hospitals, where temperature settings can be adjusted for each private room, maintaining comfort and achieving high energy efficiency. This system is widely used and popular due to its energy-saving benefits.

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Connection of Refrigerant Copper Pipes

Refrigerant copper pipes have higher pressure requirements compared to the fan coil unit system, and the piping must comply with technical standards such as the High-Pressure Gas Safety Act and Refrigeration Safety Regulations. Additionally, special attention must be paid to the connecting process, including storage, protection, and maintaining dry, clean, and airtight conditions.

The pipes used are copper pipes (JIS H CT standard) coated with air conditioning refrigerant insulation (JIS A A-PE-C-2 compliant).

The Japan Copper Development Association (JCDA) defines the quality and testing methods of the pipes through JCDA and JCDA . Two types of pipes are specified: straight pipes with a length of 4 meters and coiled pipes with a length of 20 meters for sizes below 19.05mm. Coiled pipes are commonly used near indoor units for easier handling.

For connecting to indoor units, the common traditional methods are flaring and welding. In recent years, fire-free methods have gradually gained popularity. The current joining methods and tools for refrigerant copper pipes are as follows: (details not provided in the original text).

The process involves inserting a copper pipe into a fitting or an expanded socket created by an expander. The connection is then created by heating the socket using burning acetylene gas and filling the gap with phosphor-copper solder. This work should be carried out by a qualified welder or someone who has completed gas welding training, as mandated by labor safety and health regulations.

Various precautions need to be taken during the process, such as carefully controlling the heating temperature and ensuring that no oxidation film forms inside the pipe by flowing nitrogen gas appropriately. Skilled and experienced professionals are required for this type of work. This method is commonly used for connecting copper pipes to outdoor units or connecting branches inside buildings and has been widely used in many construction sites for a long time.

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The process involves inserting a flare nut onto the pipe and then expanding the pipe end using either an electric or manual flaring tool. The flared pipe end is then connected to the equipment's male screw by tightening the nut. The inner surface of the flare and the equipment's connection end form a metal seal. It is essential to tighten the nut with a specified torque.

Insufficient tightening may result in refrigerant leakage, while excessive tightening could lead to damage to the flared portion. Therefore, it is necessary to use a torque wrench to manage the tightening torque of the nuts for each size. Copper pipe sizes ranging from 6.35mm to 15.88mm are commonly used for connecting pipes with various equipment.

Reasons for the Transition of Refrigerants

Refrigerants used have evolved from old refrigerants (CFC) to alternative refrigerants (HCFC) and then to new refrigerants (HFC), and air conditioning equipment manufacturers have released energy-efficient new models compatible with the new refrigerants. Due to the refrigerant transition, the maximum operating pressure increases to 4.3 MPa, but with improved efficiency, there is also the benefit of being able to use piping one size smaller than the old piping.

The transition of refrigerants is driven by two environmental issues. The issue of ozone depletion has been addressed by HFCs, achieving zero ozone depletion potential (ODP). However, the global warming potential (GWP) has not yet been eliminated. Even the latest refrigerant R32 has a GWP of 675, which is one-third of other new refrigerants, but the urgency to stop global warming remains.

With the amendment of the Fluorocarbon Emission Control Law, equipment managers are legally responsible for refrigerant management during air conditioning equipment use, removal due to equipment lifespan, refrigerant recovery, and proper disposal of fluorocarbon gas.

It is crucial for refrigerant piping to be absolutely leak-free during installation and use.

The popularization / adoption of fireless joints

When implementing equipment replacement work with welding, there is a fire risk to consider. The process of removing flammable materials and implementing fire protection measures requires effort. For those who want to minimize these losses and do the work without requiring special skills or experience, our company introduced "O'zzone Boy" in .

Since its introduction, O'zzone Boy has evolved significantly in two stages, improving its performance while maintaining ease of installation and offering the more affordable "Reiwa O'zzone" in . In , the JCDA performance standard for this category was established, and both O'zzone Boy and Reiwa O'zzone obtained JCDA performance certification in and , respectively.

Through such improvements and a track record of safety and security, we have gained the support of repeat customers, making "O'zzone Boy" a trusted brand for fire-free installations. Additionally, we have developed and launched the "Aluminum O'zzone Boy," which is designed for use with aluminum pipes, as there has been a trend towards using aluminum pipes for refrigerant piping due to the rise in copper prices.

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I am looking for suggestions of methods to provide joint restraint on an existing 14" AC watermain. The watermain currently transitions from AC to PVC by a transition coupling which is approxiamately 10' from an existing gate valve on the AC side. The PVC portion of the watermain must be removed so a stormwater pond can be constructed. The pond will be over 15' deep. Since there is an existing tee prior to the valve and that AC pipe must remain in service during construction the restraints need to be in place prior to removing the PVC pipe.

Does anybody have any suggestions of how to accomplish this? I would like to use Stellar Clamps connected by all thread rods but haven't had any luck in locating a manufacturer.
If this installation is somewhere in the USA or other regulated countries, you are perhaps already aware that there are multiple issues involved (OSHA, state regulatory, and others etc.) in addition to questions related to self-restraint etc. in dealing with existing asbestos cement (AC) water and even some other service AC pipelines. I do not profess to be an expert in these AC issues (other than being aware of some of them!), and if you have not done so I would strongly suggest you carefully read all governing regulations and maybe even seek out some actual experts/authorities etc. for dealing with and/or disturbing etc. this pipe.
However, I can see some of these issues as potential obstacles to the number of "takers" you might get to help you out with merchantable restraint devices to work on this pipe (at least on the list so far this appears to be zero!)
If you don't find same or if it is not possible for some reason to parallel or otherwise replace enough of this piping with some other suitable contemporary piping (for example a suitable restrained length of contemporary piping now listed suitable for carrying potable water, as is apparently being done in many parts of the world), perhaps you could consider e.g. some sort of "external anchorage" of all pressure thrust foci (such as a valve that might be closed with pressure against the closed gate?)involved. What exactly this external anchorage could be may be limited some by the configuration(s) of the actual thrust foci involved, the pressure, available space, soil conditions, constructability, the fragility (with regard to construction support and digging around/under etc.) of the existing AC, and of course the structural/mechanical imagination/experience etc. of the designer.
Perhaps something else that might be considered is sliplining or pipebursting the existing pipe with some length of near the same size or smaller self-restrained line, if this is allowed in the area by regulatory folks and can be tolerated by hydraulic conditions etc. While I have no specific experience with sliplining of AC pipe either, I wonder that if a length of new piping can be slid up inside the end of an existing buried, I suspect maybe long undisturbed, AC pipeline, might that new restrained piping even be somehow grouted in place to aid in the anchorage you seek?