What Fire Protection Steel Pipe Is
Fire protection steel pipe is the pipe used in hydrant systems, sprinkler systems, fire water supply mains, foam systems and standpipes. In most cases it is a galvanized or coated carbon steel pipe, either welded or seamless, produced to a standard product specification. What makes it a fire protection product is the combination of that product standard with the mechanical, dimensional and testing requirements of the fire protection code adopted by the project, plus the certification the pipe must carry before it can be installed.
Materials and Standards by Region
| Region | Common pipe standards | Common grades | Coating practice |
|---|---|---|---|
| China | GB/T 3091-2015 welded steel pipe, GB/T 8163-2018 seamless steel pipe | Q235B, 20# | Hot dip galvanized to GB/T 13912, or coated for buried service |
| United States | ASTM A53 galvanized and seamless or welded pipe, ASTM A106 seamless pipe for high temperature service | A53 Grade A and B, A106 Grade B | Galvanized to ASTM A53, with ASTM A153 for coated fittings |
| Europe | EN 10255 welded tubes for threading, EN 10217 welded pressure tubes, EN 10216 seamless pressure tubes | EN 10255 series, EN 10216-2 grades | Hot dip galvanized to the applicable EN coating standard |
| Australia | AS 1074 steel tubes and tubulars for ordinary service | AS 1074 grades | Galvanized, with WaterMark certification for fire service |
Chinese hydrant and sprinkler networks commonly use Q235B galvanized welded pipe to GB/T 3091-2015, while overseas projects may call for ASTM A53 Grade B or EN 10255 tube. Where the system operates at higher temperature or pressure, such as in a pump room or a foam system, seamless pipe to GB/T 8163-2018 or ASTM A106 may be specified instead.
Coating and Corrosion Protection
The zinc coating is what keeps a fire water pipe serviceable, because the base material is ordinary carbon steel. GB/T 13912 sets coating requirements as an average mass per unit area together with a minimum individual value, and the required value varies with the steel thickness. ASTM A53 contains its own coating requirement for galvanized pipe, and ASTM A153 covers zinc coatings on iron and steel hardware. Market specifications frequently quote minimum layer thicknesses such as 60, 70 or 85 microns; whichever figure is used should come from the project specification or from the coating standard that applies to the delivery, and inspection documents should report both the average mass and the minimum local thickness.
Buried fire water mains need more than galvanizing. Fusion bonded epoxy, three layer polyethylene coating or a bitumen wrap combined with cathodic protection is normally specified where the pipe passes through aggressive soil. Threading cut through a galvanized layer leaves bare steel, so exposed threads must be re-protected with a zinc rich coating after assembly, and field welds must be coated and inspected in the same way.
Pressure Rating, Testing and Connections
Chinese fire water design codes, including GB 50974, base the hydrostatic test on a multiple of the working pressure, typically 1.5 times the design pressure, and design pressures for hydrant and sprinkler networks are commonly up to about 2.5 MPa. International practice follows the same principle: ASME B31.3 requires a hydrostatic test at 1.5 times the design pressure, and petrochemical fire water systems are sometimes tested at 4.0 MPa or more. The governing test pressure is the one written into the project specification, and it should be stated on the pipe order along with the test duration.
Connections matter as much as the pipe. Grooved couplings are widely used and are specified to CJ/T 156 in China. Threaded joints follow GB/T 7306 for pipe threads, and flanged joints use ANSI/ASME B16.5 in US practice or EN 1092-1 in European practice, with gaskets and bolting selected to match. Both grooved and threaded systems depend on wall thickness, so the order must state whether the pipe is to be threaded, grooved or welded.
Certification and Approval
Certification is where fire protection pipe differs most from ordinary pipe. In China, products within the mandatory certification catalogue for fire protection products must carry CCC certification, with product standards such as the GB 5135 series applied, and installation is checked against the applicable GB 50xxx construction and acceptance codes for fire protection systems. In North America, UL listing and FM approval are normally required for sprinkler pipe and fittings. In Europe, CE marking under the Construction Products Regulation is required, with the EN product standard cited on the declaration of performance. In Australia, pipe to AS 1074 for fire service must satisfy WaterMark requirements. Because testing and audit take time, the applicable scheme should be settled before the order is placed.
Selection and Fabrication Pitfalls
Ordering general purpose pipe when the specification requires a certified fire protection product. The pipe can be dimensionally correct and still be rejected by the authority having jurisdiction.
Assuming a heavier zinc coating compensates for a thinner wall. Wall thickness controls threadability and the strength of a grooved joint, so it must follow the design.
Mixing pipe from different mills in one system without recording heat numbers, which destroys traceability for later inspection.
Welding galvanized pipe without removing zinc from the joint area and without adequate ventilation, and then failing to restore the coating.
Storing galvanized pipe in wet conditions, which produces white rust before installation.
FAQ
Q: What steel pipe is used for fire protection systems?
Galvanized welded or seamless carbon steel pipe is used, normally Q235B to GB/T 3091-2015 in China, ASTM A53 Grade B in US practice, EN 10255 or EN 10217 in Europe and AS 1074 in Australia, with wall thickness set by the design code.
Q: How thick must the zinc coating be?
The required coating is set by the coating standard and the project specification. GB/T 13912 states requirements as an average coating mass plus a minimum individual value that vary with steel thickness, and ASTM A53 and ASTM A153 state their own values, so the figure on the order must match the specification.
Q: What hydrostatic test pressure is required?
Chinese fire water codes such as GB 50974 normally require a test at 1.5 times the working pressure, and ASME B31.3 uses the same multiple of the design pressure. Petrochemical fire water specifications may require 4.0 MPa or more.
Q: Which connection method is used for fire pipe?
Grooved couplings to CJ/T 156, threaded joints to GB/T 7306, and flanged joints to ANSI/ASME B16.5 or EN 1092-1 are all common. The chosen method sets the minimum wall thickness that should be ordered.
Q: Is certification needed for exported fire protection pipe?
Yes in most markets. UL listing and FM approval are typical for North America, CE marking under the Construction Products Regulation for Europe, and WaterMark with AS 1074 for Australia.
Q: Can black pipe be used instead of galvanized pipe?
Black pipe is acceptable only where the design permits it or where a separate protective coating is applied, such as buried pipe with epoxy or three layer polyethylene coating. Above ground fire water pipe is normally galvanized.
