Guide To Fire Fighting Pipes and Fittings | JIANZHI

Fire-fighting pipes and fittings are the most basic components of the fire-fighting system, connecting fire-fighting equipment, and delivering fire-fighting water. 

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Due to special requirements, the thickness and material of fire pipelines have special regulations, and they are sprayed with red paint. Fighting Pipes and Fittings must have the characteristics of pressure resistance, corrosion resistance and high temperature resistance.

Standardized fire piping facilities

As a standardized industrial product, fire pipes and fittings are strictly divided into different specifications. If buyers want to buy suitable products, they must have a clear understanding of these specifications. 

Now, let's follow this guide to learn what to look out for when selecting fire pipes and fittings.

1. Selection of Fire Fighting Pipe Types

Pipe type is an important factor affecting the quality of pipe grooved connections. Most of today's fire pipeline facilities are connected by grooves. For the advantages of grooved connections, you can refer to the following:

Grooved Couplings: The Fastest Way to Connect Pipe

The groove connection method is suitable for a wide range of pipeline types. "Technical Regulations for Grooved Connection Pipeline Engineering" (CECS151:) points out: "The groove connection method can be used for galvanized welded steel pipes and welded steel pipes, galvanized seamless steel pipes and seamless steel pipes, stainless steel pipes, etc.” However, since the form of the weld has a certain influence on the quality of the steel pipe groove connection, the weld seam of the welded steel pipe is prominent, which is not conducive to the pressure groove of the steel pipe. Therefore, seamless steel pipes should be the first choice during installation and construction, followed by straight seam welded pipes, and spiral welded pipes should be avoided. If it is necessary to use the spiral welded pipe, the corresponding grooved pipe fittings should also be used.

2. Quality requirements for Fire Fighting pipes

Since the grooved pipe fitting is engaged with the outer wall of the pipe, excessive deviation of the outer diameter of the pipe will cause the pipe to not match the clamp, which will cause the joint to seep. In addition, unqualified pipe material, weak galvanized layer, and insufficient thickness of the pipe wall may cause the pipe to break, the galvanized layer to fall off in large quantities, or the high-frequency weld to crack, which will eventually lead to water seepage or rupture of the joint. Therefore, strict control of pipe quality is essential. All kinds of pipes should comply with the corresponding national standards. For example, galvanized welded steel pipes should meet the requirements of "Galvanized Welded Steel Pipes for Low-Pressure Fluid Transport" (GB/T), and seamless steel pipes should comply with "Seamless Steel Pipes for Fluid Transport" ( GB/T), the plastic-coated galvanized welded steel pipe and the plastic-coated seamless steel pipe shall meet the requirements of "plastic-coated composite steel pipe for water supply" (CJ/T). In addition, the wall thickness of the steel pipe shall also meet the minimum wall thickness requirements.

3. Roundness control of nozzles

Insufficient roundness of the nozzle is an important reason that affects the quality of the pipe groove connection. Before construction, the roundness of incoming pipes should be checked. The inspection can be carried out according to the following methods: Divide the pipe section into 8 equal parts, measure 4 diameters respectively, and compare them with the standard value. Where the roundness is not up to standard pipe sections should be rounded or cut off. The roundness of the pipeline is not up to standard, which is often caused by the collision of the pipeline or the extrusion of the pipes during transportation or loading and unloading. China has good experience in pipe transportation. The engineers and technicians in this country have adopted the method of installing a cross support frame at the pipe end, which has solved the problem of pipeline compression and deformation, which is worth learning and popularizing.

4. Choice of sealing ring

The sealing ring used in the grooved pipe joint realizes the sealing performance of the system by increasing the pressure. From the cross-section, it belongs to the "C" type design. The higher the pressure, the better the sealing performance. The material used for the sealing ring can be determined according to the medium conveyed by the pipeline, and different materials have different letter codes on the sealing ring. For example, EPDM rubber (code E, black) is usually used in fire engineering systems; silicone rubber (code S, the sealing ring material of the pressure cooker, is milky white) for drinking water; Nitrile rubber (code D, orange); natural rubber (code N, black). Therefore, in fire protection projects, black EPDM rubber rings must be used.

Fire fittings with black EPDM seals

5. Rated working pressure of Fire Fighting grooved fittings

Rated working pressure refers to the maximum allowable working pressure of grooved fittings under working conditions, expressed in megapascals (MPa). At present, the rated working pressure of grooved fittings produced by various manufacturers in China is basically the same, namely, Grooved pipe fittings (such as elbows, tees, crosses, etc.) are generally 2.5Mpa; while threaded reducing tees and crosses; threaded mechanical tees and crosses; threaded flanges and other threaded pipe fittings are usually is 1.6MPa. The number of kilograms usually mentioned in engineering refers to the pressure of kilograms per square centimeter. Its code is Kgf/㎝ 2, and its relationship with Mpa is 1Mpa≈10 Kgf/ cm2.

The pipe fittings show a pressure capacity of 2.5MPA

6. Standard for grooved pipe fittings:

Chinese Standard: Grooved pipe fittings belong to the automatic sprinkler system, design standard GB .11-; technical specification GB/T -.

International Standard: American Design Standard AWWA C606; International Standard ISO .

Groove connection standard: ASME B36.10, ASTM A53-A53M, ISO.

7. Material standard of grooved pipe fittings

China requires that the material grade should not be lower than QT450-10;

Tensile strength σb (MPa): ≥450

Conditional yield strength σ0.2 (MPa): ≥310

KOXY Product Page

Elongation δ (%): ≥10

Hardness: 160～210HB

Chemical element content: carbon C: 3.70-4.00; Si: 2.15-2.93; Mn: 0.46-0.66; S: 0.010-0.016; P: 0.027-0.07; Mg: 0.027-0.050; Re: 0.026～0.043

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I believe that after reading this guide, you already have a certain understanding of fire fighting pipes and fittings. 

If you want to know more, please click the link below to enter the official website of Jianzhi Group, where there is more knowledge about fire pipe fittings.

The fire protection pipe and connection fittings are mainly used to connect firefighting equipment, conveying fire fighting water and so on. It is also called fire sprinkler pipe and fittings. Due to the special requirements, the thickness and material of the fire protection pipe and fittings have special requirements. According to the regulations, the fire pipeline need to be sprayed red paint, obviously different with other pipeline. Because the fire protection pipe is often in a static state, so it is required more strict. The fire proof pipe and connection fittings must possess pressure resistance, corrosion resistance and high temperature resistance.
According to material, the fire protection pipe can be divided into ductile iron pipe, copper pipe, stainless steel pipe, alloy pipe and composite pipe, plastic pipe.

1. Installation process flow for fire pipeline system

Installation preparation → dry pipe installation → alarm valve installation → vertical pipe installation → spray layered Sexagenarian cycle pipe, hydrant and branch pipe installation → water flow indicator, fire water pump, high water tank, water pump coupling installation → pipeline trial pressure → pipeline flushing → spray head branch pipe installation ( system comprehensive test pressure and flushing ) → throttle device installation → alarm valve accessories, hydrant accessories, spray head installation → system water test

2. The connection technology of fire protection pipe and fittings

1). General connection fittings for fire pipeline

When the pipeline of fire hydrant water supply system adopts hot dip galvanized steel pipe, welding shall not be used. If the fire protection pipe adopts material that the internal wall don’t carry out anti-corrosive treatment, it can be welded for connection. But the pipeline welding should meet the relevant requirements. Automatic sprinkler system pipe cannot be welded, it should use threaded, flange and other connection.

In hydrant water supply system, hot dipped galvanized steel pipe that the pipe diameter is greater than 100 mm should be connected by flange connection or groove connection.
If the pipe diameter is greater than 100 mm, it is not clearly indicated in automatic sprinkler system, threaded connection cannot be used. It is only required that flange connection or groove connection point shall be arranged at a certain distance on the pipe whose diameter is greater than 100 mm.

When pipeline of the fire hydrant water supply system and automatic sprinkler system adopt flange connection, the threaded flange is recommended. AS the welding flanges are used, the second zinc plating shall be carried out.

If any fire proof pipe section need to change the pipe diameter, the connection pipe fittings that complied to the standard shall be used.

2). Groove (clamp) connection for fire protection pipe and fittings

The groove connection (pipe joint) and fire steel pipe groove depth shall conform to the requirements of the groove type pipe joint. The maximum working pressure of groove pipe joint with nominal diameter of DN250 or less is 2.5 MPa. The maximum working pressure of groove pipe joint with nominal diameter of DN300 or more is 1.6 MPa.

Flexible joints can be used for vibration places and buried fire protection pipe, rigid joint fittings shall be adopted in other places. When the rigid joints fittings are used, a flexible joint shall be arrange for every 4-5 rigid joints.

3). Threaded connection in fire pipeline systems

For fire proof pipe, the hot-dip galvanized welded steel pipe or hot-dip galvanized seamless steel pipe whose inner and outer wall diameter is less 100 mm can use threaded connection. When the hot-dip galvanized ERW steel pipe is adopted in the system, the malleable iron threaded pipe fittings can be used. If the hot-dip galvanized seamless steel pipe is adopted, the forged steel thread pipe fittings can be used.

If the wall thickness of steel pipe is less than the delta < Sch30 (DN≥200mm r) or less than the delta < Sch40 (DN < 200 mm), the threaded connection shall not be used.

When the fire protection pipe adopts 55 °taper pipe threads (Rc or R), the threaded interface can be sealed with PTFE. When the pipeline used 60 °taper pipe threads (NPT), it is appropriate to use the sealant as the sealing of the threaded interface. The sealing strap shall be applied on the male thread.

The fire pipe that diameter is less DN50 shall not use threaded union, the monomer reducing joint shall be used at the variable diameter of pipe.

4). Welded or flange joint connection fittings

According to connection, the flange can be divided into flat welding flange, welded flange and threaded flange, etc. The selection of flange muse comply with steel pipe flanges standard, steel butt welded seamless pipe fitting standard, Teflon coated gaskets for pipe flanges standard.

If the hot-dip galvanized steel pipe adopts flange connection, the threaded flange shall be selected. When the fire pipeline system used the fire proof pipe that the internal wall are not carried out anti-corrosive treatment, the welding connection can be used.

For more information, please visit Fire Protection Pipe fittings & One-stop Piping System Supplier.