Piping, Fittings, and Valves

Piping, Fittings, and Valves

Chapter Introduction

This chapter covers all the essential knowledge regarding pipes, fittings, and valves used in automatic sprinkler systems. You must master the materials, dimensions, assembly methods, selection criteria, and requirements of the Canadian Electrical Code, Part I — no, rather the CSA B149.1 Automatic Sprinkler Installation Code — wait, it is actually the NFPA 13 standard adopted in Canada by the National Building Code of Canada (NBC) , and the CSA B149.1 standard does not apply to sprinklers. The applicable standard is NFPA 13, Standard for the Installation of Sprinkler Systems , as adopted by Canadian codes. Remember this: in Canada, the design and installation of sprinklers are governed by NFPA 13 (current edition) and the National Building Code of Canada (NBC) . Provincial requirements may add to this, but the Interprovincial exam is based on these national standards.

2. Types of Pipes and Materials

2.1 Carbon Steel Pipe

Carbon steel is the most common material for sprinkler systems. It is manufactured according to ASTM A53 (welded or seamless pipe) and ASTM A135 (electric-resistance-welded pipe). Three types are distinguished:

Pipe Schedules: Steel pipes are classified by wall thickness (Schedule). The most common in sprinkler systems are:

Nominal Size: The nominal size (DN or NPS) does not correspond to the actual outside diameter. For example, a 2" NPS pipe has an outside diameter of 2.375". The following table provides key dimensions:

NFPA 13 Rule (Section 6.1): Steel pipes must conform to ASTM A53, A135, or A795. The minimum wall thickness for sprinkler systems is Schedule 10 for pipes 2" and smaller, and Schedule 7 for pipes 3" and larger, provided that threading is not required. If the pipe is threaded, the minimum wall thickness is Schedule 40 for diameters up to 6".

2.2 Copper Pipe

Copper is used for small systems, residential systems, and corrosive environments. Applicable standards are ASTM B75 (seamless drawn tube) and ASTM B88 (copper tube). Tube types:

NFPA 13 Rule (Section 6.3): Copper tube must be Type K or L for sprinkler systems. Fittings must be copper or bronze, and brazed joints must use a filler metal with a melting point above 540 °C (1000 °F) — that is, silver brazing, not soft soldering.

2.3 CPVC Pipe (Chlorinated Polyvinyl Chloride)

CPVC is a thermoplastic used for residential and light hazard sprinkler systems. Standard: ASTM F442 and CSA B137.6. CPVC is approved by NFPA 13 for residential systems (Sections 6.5 and 7.5) and light hazard systems.

Important Characteristics:

2.4 Ductile Iron Pipe

Used primarily for underground supply lines. Standard: AWWA C151 (ductile iron) and ASTM A536. Fittings conform to AWWA C110 or C153. Ductile iron is resistant to external corrosion and can withstand significant soil loads.

2.5 Stainless Steel Pipe

Used in corrosive environments (chemical industries, coastal areas). Standards: ASTM A312 (seamless and welded pipe) and ASTM A778 (welded pipe). Fittings are stainless steel of the same series (304, 316). Assembly is done by TIG welding or mechanical fittings.

3. Fittings and Assembly Methods

3.1 Threaded Fittings

Threaded fittings are used for steel pipes 2" and smaller. Threads must conform to ASME B1.20.1 (NPT — National Pipe Thread). Fittings made of forged steel or malleable iron conform to ASME B16.3 (malleable iron) and ASME B16.11 (forged steel).

Types of Threaded Fittings:

Assembly Requirements:

NFPA 13 Rule (Section 6.2.3): Malleable iron threaded fittings are permitted for pipes up to 2". For larger diameters, fittings must be forged steel or welded.

3.2 Welded Fittings

Welding is used for steel pipes 2 ½" and larger, or where the installation requires it. Permitted processes:

Qualification Requirements: Welders must be qualified according to CSA W47.1 (certification of welding companies) and CSA W47.2 (qualification of welders). The Interprovincial exam may ask you to know these standards.

Joint Preparation: For pipes 3" and larger, a bevel of 37.5° is required. The root gap must be 1/16" to 1/8" depending on thickness.

NFPA 13 Rule (Section 6.2.4): Welding must be performed in accordance with the ASME Boiler and Pressure Vessel Code, Section IX or CSA W47.1. Welds must be free of cracks, porosity, and lack of penetration.

3.3 Grooved Fittings

Mechanical grooved fittings have become the standard for modern sprinkler systems. They use grooved couplings and grooved fittings conforming to ANSI/AWWA C606 (grooving).

Types of Couplings:

Grooving Procedure:

Standard Groove Dimensions (for Schedule 40 pipe):

NFPA 13 Rule (Section 6.2.6): Grooved fittings must be installed according to the manufacturer's instructions. Couplings must conform to ANSI/AWWA C606 and gaskets must be EPDM or nitrile, compatible with the fluid.

3.4 Flanged Fittings

Flanges are used for connections to equipment (pumps, valves, risers) and for diameters 2 ½" and larger. Standards: ASME B16.5 (flanges and flanged fittings) and ASME B16.47 (large-diameter flanges).

Types of Flanges:

Bolting: Bolts must be zinc-plated carbon steel or stainless steel, conforming to ASTM A193 (bolts) and ASTM A194 (nuts). Tightening torque must follow the manufacturer's recommendations, tightening in a star pattern.

3.5 Compression and Push-Fit Fittings

Compression fittings are used for small-diameter copper tubing. Push-fit fittings are increasingly common for quick repairs. They must conform to ASSE 1061 or CSA B125.3.

4. Valves

4.1 Valve Classification

Valves are classified according to their function:

4.2 Gate Valves

Gate valves are used to isolate sections of the system. They must conform to MSS SP-80 or AWWA C500. Characteristics:

NFPA 13 Rule (Section 8.16.1): Each floor, each zone, and each system must be provided with a gate valve. Valves must be identified with a sign indicating the system they control.

4.3 Butterfly Valves

Butterfly valves are used for diameters from 2" to 24" and larger. They are more compact and lighter than gate valves. Standards: AWWA C504 (butterfly valves) and MSS SP-67.

Mounting Types:

Locking: Butterfly valves must be equipped with a locking device (padlock) to prevent accidental closure.

4.4 Check Valves

Check valves prevent the backflow of water. Types:

NFPA 13 Rule (Section 8.16.5): A check valve must be installed on each water supply to prevent backflow. Check valves must be installed in the direction of flow, with the arrow indicating direction.

4.5 Test Valves and Inspection Valves

Inspector's Test Valve: Simulates the opening of a sprinkler to verify alarm operation. It must be installed at the end of the most remote line of the system, with a discharge orifice of the same diameter as the smallest sprinkler in the system.

Main Drain Valve: Allows the system to be drained and verifies supply pressure. It must be installed at the base of the riser.

4.6 Alarm Check Valves

The alarm check valve is a special check valve that triggers a hydraulic (water motor gong) or electric alarm when water flow occurs. It is installed on the main riser, between the gate valve and the system.

Components:

NFPA 13 Rule (Section 8.17.2): The alarm check valve must be installed on each sprinkler system, unless the system is equipped with a vane-type waterflow detector.

5. Supports and Hangers

5.1 General Requirements

Pipes must be supported to prevent deformation, breakage, and excessive stress. Supports must conform to NFPA 13, Section 9.1 and MSS SP-58 (pipe hangers and supports).

Maximum Support Spacing:

NFPA 13 Rule (Section 9.1.2.1): The maximum spacing between supports for steel pipes is 12 ft for diameters 1" to 1 ¼", and 15 ft for diameters 1 ½" and larger.

5.2 Types of Supports

5.3 Specific Requirements

6. Hydraulic Calculations and Sizing

6.1 Basic Principles

The sizing of sprinkler systems is based on hydraulic principles. Key formulas:

Flow Rate: Q = A × V

Pressure Loss: The Hazen-Williams formula is used for sprinkler systems:

ΔP = 4.52 × Q^1.85 / (C^1.85 × d^4.87)

Required Pressure: The pressure at the most hydraulically remote sprinkler must be at least 7 psi for standard sprinklers (NFPA 13, Section 7.2.3.2).

6.2 Design Density and Area

The most common sizing method is the density/area method:

Design Example: For an ordinary hazard (group 1), the density is 0.15 gpm/ft² over an area of 1500 ft². The total required flow is:

Q_total = 0.15 × 1500 = 225 gpm

6.3 Maximum Velocity

The velocity of water in pipes must not exceed 20 ft/s to prevent erosion and noise (NFPA 13, Section 7.2.3.1). For alarm systems, velocity is limited to 10 ft/s in risers.

6.4 Maximum Pressure

The maximum working pressure for a sprinkler system is generally 175 psi (12 bar). Beyond this, special components are required (high-pressure valves, high-pressure sprinklers).

7. Testing and Commissioning

7.1 Hydrostatic Pressure Test

Before commissioning, the system must undergo a pressure test:

7.2 Operational Test

7.3 Flow Test

The flow test is performed on the riser to verify that flow and pressure conform to the design. Results must be recorded in a report.

8. Common Pitfalls to Avoid

Here are the most frequent errors on the Interprovincial exam:

9. Summary

10. Exam Tips

11. Application Exercises

Exercise 1: A 4" Schedule 40 steel sprinkler system is to be installed. What is the inside diameter of the pipe?

Solution: From the table, for NPS 4", the inside diameter is 4.026 in.

Exercise 2: An ordinary hazard (group 1) sprinkler system has a design density of 0.15 gpm/ft² over an area of 1500 ft². What is the total required flow?

Solution: Q = 0.15 × 1500 = 225 gpm.

Exercise 3: A 3" steel pipe carries a flow of 100 gpm. Is the velocity acceptable?

Solution: Pipe cross-sectional area (inside diameter 3.068 in): A = π × (3.068/2)² = 7.39 in². Convert to ft²: 7.39 / 144 = 0.0513 ft². Velocity V = Q / A = (100 gpm × 0.1337 ft³/gal) / 60 s / 0.0513 ft² = 4.35 ft/s. The velocity is below 20 ft/s, therefore acceptable.

Exercise 4: What is the minimum hydrostatic test pressure for a system with a working pressure of 150 psi?

Solution: Test pressure = 200 psi (since 200 > 150 + 50 = 200). The test pressure is therefore 200 psi.

12. Glossary of Key Terms

13. Normative References

This chapter has provided you with the essential knowledge on piping, fittings, and valves for the Red Seal exam. Review the tables, memorize the standards, and practice the calculations. Good luck with your preparation!