Fire Protection Pipe and Connection 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.