SECTION 21 0500 – COMMON WORK RESULTS FOR FIRE SUPPRESSION
- General Description
- Pipe Sleeves and Seals
- Pipe Hangers and Supports
- Mechanical Couplings
- How to Specify
This section includes pipe materials and fittings normally found in water-based fire suppression systems. It is intended to cover materials encountered in more than one section to reduce repetition.
Rigid steel sprinkler piping conforms to ASTM A53, A135, or A795. It is typically black in color with rigid characteristics. Conversely, light-wall steel piping possesses a silvery appearance due to its galvanized exterior and is also manufactured to meet the requirements of ASTM A135 but does not conform to the dimensional requirements of established pipe schedules. Other sprinkler piping types that are available for use in construction also comply with these ASTM Standards. All types of steel piping have unique properties, from joining methods, to weight, to wall thickness, and to inside and outside diameter dimensions. This Section describes steel pipe applications appropriate for NFPA 13 light hazard occupancies including NFPA 13R. Steel piping for use in sprinkler systems is not specified by NFPA in sizes below 1 NPS (25 DN). The piping is pressure rated at 175 psi (1.21 MPa) and has a melting point ranging from 2600 degrees F (1427 degrees C) to 2800 degrees F (1538 degrees C). Steel piping has the lowest coefficient of linear expansion (CLE) of the piping discussed in this evaluation. As an example, a section of piping 100 ft (30.5 m) in length at a temperature of 40 degrees F (4.4 degrees C) increases only 0.63 inches (16 mm) in length when heated to a temperature of 120 degrees F (49 degrees C). The rigidity and mechanical strength of steel piping when compared to PVC under similar installation conditions, minimizes or prevents any damage resulting from banging, dropping, or stepping on the pipe. This inherent rigidity can be counter-productive resulting from routing the piping around numerous obstructions during installation, but is more than made up for due to ultraviolet (UV) exposure tolerance as compared to CPVC.
Copper tubing was approved in 1961 by NFPA for use in fire sprinkler systems. It conforms to ASTM B88, and can be best described as a brownish, malleable metal. Copper tube sizes are based on the CTS (Copper Tubing Size) system where the tube’s outer diameter is 0.125 inches (3.18 mm) greater than its nominal size. There are three types of tubing available, namely K, L, and M. Type K has the thickest wall, followed by Type L having a thinner wall, and lastly, Type M having the thinnest wall. Thinnest wall translates to least cost which results in Type M being the most commonly used in fire sprinkler systems. All three Types are available in drawn (hard) temper. Types K and L are also available in annealed (soft) copper. An advantage that copper has over steel is the flexibility of types K and L annealed tubing in smaller diameters where bending is required. Copper tubing has a CLE of approximately 1-1/2 times that of steel and melts at 1980 degrees F (1082 degrees C). As an example, a 100 ft (30.5 m) section will expand 0.90 inches (23 mm) when heated from 40 degrees F (4.4 degrees C) to 120 degrees F (49 degrees C). Mechanical properties or performance capabilities will not be affected due to UV exposure for extended periods of time. When compared to same size, light-walled steel pipe a 1 NPS (DN 25) type M copper tube weighs 0.46 lb/ft (0.68 kg/m) or less than 1/3 the weight. Exercise normal care during the installation phase since copper piping is not as prone to damage from dropping or stepping on as is CPVC.
CPVC pipe listed for use in fire sprinkler piping is classified as a rigid, thermoplastic material that is lightweight and bright orange in color. Since 1959, CPVC has been used in both cold and hot water applications, and in industrial applications since 1962. The first use in residential applications came in 1984 which resulted in being listed by Underwriters Laboratories (UL). CPVC has a standard dimension ration (SDR) of 13.5 where the SDR is the ratio of average outside pipe diameter to wall thickness. CPVC conforms to ASTM F442, and is sized according to the NPS system. Based on information supplied from the manufacturer, CPVC has a heat distortion temperature (HDT) of 217 degrees F (103 degrees C) which is the temperature at which the pipe begins to soften and lose strength. HDT is measured in accordance with ASTM D648. The CLE is more than 5 times that of steel and approximately 3 times that of copper. When exposed to significant differences in temperature, expansion or contraction is noticeable to the naked eye. To put things into perspective, when heated from 40 degrees F (4.4 degrees C) to 120 degrees F (49 degrees C), a 100 ft (30.5 m) length will expand 3.3 inches (84 mm) along the length of the pipe with negligible change in outer diameter. Unlike steel and copper piping, CPVC piping warrants special installation considerations due to the thermal expansion properties. When compared to steel and Type M copper, 1.0 NPS (DN 25) CPVC pipe weighs just over 1/5 the weight of light-wall steel and a little more than 1/2 the weight of Type M copper of comparable size. Above average care is required when handling and installing CPVC pipe. Stepping on, dropping, or dropping objects on this piping material could easily result in splitting, gouges, or scratches, thus requiring rework and/or replacement to avoid comprising system integrity. Unlike rigid steel and copper piping, prolonged exposure to UV may diminish drop impact resistance and reduce flexibility; however, the long-term hydrostatic strength capability is still maintained. During shipping, CPVC sprinkler piping is shipped in bundles and wrapped in an opaque covering or placed in white cardboard boxes for UV protection; the total lineal footage of piping in each bundle depending on pipe size. Coating the piping with latex paint is acceptable, however, it is recommended to consult with the manufacturer prior to applying other types of paint, sealants, or fire stop materials to the pipe.
Ductile iron pipe is typically used in potable water transmission and distribution and conforms to AWWA C151/A21.51. It is a direct development of earlier cast iron piping, which it has superseded. The material used to manufacture the pipe can be described by the nodular or spherical nature of the graphite within the iron. In general, the pipe is manufactured using centrifugal casting in resin or metal molds. Protective external coatings (asphalt, water-based paint, or bonded zinc) and internal linings (cement mortar) are often applied to prevent corrosion. Loose, polyethylene sleeving (LPS) may also be used to encase the piping when located in highly corrosive environments. A lifespan in excess of 100 years has been estimated for the pipe when encased in LPS. The sizing of ductile iron pipe is in accordance with a dimensionless term known as Pipe Size or Nominal Diameter (DN) which is roughly equivalent to the internal diameter of the pipe in inches or millimeters. The pipe’s external diameter is kept constant between changes in wall thickness to maintain compatibility in fittings and joints; hence the internal diameter can vary significantly from its nominal size beginning at 3 inches (76 mm) up to 64 inches (1625 mm) in increments of 1 inch (25 mm), minimum, all in accordance with AWWA C151/A21.51. Ductile iron pipe is typically manufactured exclusively from recycled material which includes recycled iron and scrap steel. The piping can be recycled after use. Several studies have been conducted beginning in 1995, comparing ductile iron’s impact on the environment as compared to other piping materials such as concrete, cast iron, PVC, and high density polyethylene (HDPE). Factors taken into account included CO2 emissions during manufacturing, energy consumed, “global warming potential” based on emissions from manufacturing, transportation, installation and natural resource depletion, including taking the service life of the piping into account. As a result, In November 2012, ductile iron pipe manufactured in the United States received certification as a sustainable product from the Institute for Market Transformation to Sustainability.
Pipe sleeves usually consist of a short length of pipe that passes through a wall or barrier expressly for the purpose of inserting another pipe through it. The sleeve is installed before a concrete pour to avoid additional costs and construction delays associated with core drilling, patching or chopping. Pipe sleeves are typically manufactured or fabricated from Schedule 40 carbon steel pipe or 1/4 inch (6.35 mm) rolled steel plate. Alternative materials may include stainless or galvanized steel, brass, PVC, cast iron, etc. The various types of pipe sleeves specified in this Section are described herein according to the material from which the sleeve is constructed and the application. Materials of construction that may be specified include plastic, sheet metal, moisture-resistant fiber, zinc-coated, cast iron, brass and galvanized steel. Sleeves of light-gauge sheet metal may also be used as long as consideration is given to the ability to withstand the concrete forming and pouring process. Wall sleeves penetrating water-proof floors and exterior concrete walls need to be fabricated with full-circle, continuously welded, water-stop plates which maintain tight water-sealing on the outside diameter of the sleeve and also serve as a point of anchorage to prevent thrust movements. Always install sleeves that pass thru interior masonry and concrete walls such that they are flush with both wall surfaces or as dictated by the fire-stop system design for that particular scenario. It is always very important to coordinate the design of the light-gauge steel sleeves with the requirements dictated by the fire-stop design. Passage of debris and fluid between floors is prevented by extending the sleeve a minimum of 4 inches (102 mm) above finished floor. It is vital to always reference the fire-stop design for the fire-stop installation location since the location may be required at the floor elevation instead of the top of sleeve. Aside from fire-stop materials and water-sealants, sleeve packing materials prevent the intrusion of air, rodents, and foreign objects. They provide cathodic protection, anchorage support, corrosion resistance, vertical piping support via riser clamps, shock (vibration and sound) absorption, and accommodate longitudinal pipe movement due to thermal effects. Common packing materials consist of casing boots, link seals, and mastics. The project specifications determine the types of materials to be used in the sealing of the annular space between the sleeve and pipe.
Requirements for sleeves in fire protection piping are minimal when compared to plumbing and HVAC piping systems. The primary application in fire protection piping is to maintain the integrity of fire rated walls and floors. When it is required to penetrate fire-rated floors and walls with piping, a through-penetration fire-stop system is required. This fire-stop consists of a specific, field-installed assembly of materials designed to prevent the spread of fire through fire-rated openings. These systems also minimize smoke flow through the penetration. Upon passing the fire-stop system ASTM E814 test standard, it is assigned a fire and temperature and in some cases an air leakage rating. The hourly ratings are typically installed to be equal to the rating of the wall or floor.
Handy Rules of Thumb:
- In underground exterior wall penetrations, watertight piping penetrations are vital.
- In new construction, cast-in-place pipe sleeves with integral water-stop need to be provided. Appropriate over-sizing of the sleeve is required for use of link-seal between sleeve and piping.
- In existing concrete, where concrete can be core drilled and properly sealed with a link-seal, a sleeve may not be required.
- In renovation work for new floors or existing concrete floors where cast-in-place sleeves were not installed, pipes penetrating above grade floors typically require “double-core” sleeves, especially in areas where floors are likely to get wet, and where water leaks to floors below would compromise operations. Piping in stairwells does not typically require floor sleeves.
Escutcheons are ornamental plates, normally installed between the sprinklers and the ceiling or wall to project a pleasing appearance. Several finish options are usually available to meet the design requirements of the project. Flush, one-piece (non-adjustable) escutcheons are used where the position of the sprinkler “escutcheon plate seating surface” (relative to the ceiling line or wall) can be fixed by adjusting the length of the interconnecting piping. Adjustable, two-piece, recessed escutcheons provide an attractive, low-profile, recessed sprinkler installation. The adjustability feature allows for minor adjustments due to ceiling or pipe pitch. They can easily be removed and reinstalled, to allow access above removable ceiling panels for servicing building equipment without having to turn off the sprinkler system and removing the sprinkler.
Since there is a limit to what can be specified, it is necessary to prepare a complete and detailed design of supports and pipe hangers required for a project. The Drawings need to show details for supports, guides, anchors, and pipe hangers including the spacing, accompanied with guidelines indicated in the specifications. Details of building attachments need to be shown, including when support of piping from concrete slab with expansion anchors is acceptable. As an example, “C” type clamp hangers are acceptable for fire protection piping when retaining clips are used.
Fire sprinkler system hangers and braces must be spaced according to the pipe manufacturer’s recommendations or in accordance with NFPA to prevent excessive sagging indicating the type of brace or hanger to be used. Both NFPA 13 and NFPA 13R require that hangers be designed to support five times the weight of the water-filled sprinkler pipe plus 250 lb (113 kg) at each point of piping support. Without exception, special listed pipe must be supported in accordance with its listing. Spacing requirements for sprinkler pipe hangers, adapted from NFPA 13, table 4-220.127.116.11, range between 12 ft (3.7 m) and 15 ft (4.6 m). The maximum distance between hangers for CPVC pipe needs to be as specified in the individual product listings in accordance with NFPA 13.
The beam strength associated with steel pipe allows for larger distances between supports than are allowed with any other type of sprinkler piping material. Due to the lack of material between the inside diameter and the root diameter of the thread, hangers need to be spaced closer for threaded light-wall steel pipe. Since copper is slightly more flexible than steel, the distance allowed between hangers in a copper tube system is less than that of steel but more than that of CPVC. Threaded light-wall steel pipe DN50 (2.0 in) or larger requires the same hanger spacing as copper tube.
CPVC Piping: The recommended hangers and braces are supplied and specifically designed by several manufacturers for non-metallic sprinkler pipe. The recommended hanger load bearing surface (minimum hanger width) for CPVC is at least 0.50 inches (12.7 mm). Less surface area may result in over-stressed pipe, thus increasing the probability of failure. Manufacturer recommendations concerning the support dimensions must be adhered to. Proper and adequate bracing at the sprinkler heads is important in CPVC fire sprinkler system installations. Since the piping is flexible material, it is especially susceptible to a reaction force (water release) upon sprinkler head activation. The manufacturer’s requirements for bracing at or near the sprinkler head needs to be adhered to.
Due to the flexibility of CPVC, it can be deflected around obstacles more readily than metal. Adequate care must be exercised to prevent excessive deflection resulting in pipe damage. Deflection of the CPVC pipe may occur by bending and snaking. Data is available from PVC manufacturers, based on ambient temperatures of 73 degrees F (23 degrees C), which indicate values for allowable deflection based on different pipe lengths. Should the allowable deflection exceed these values, failure may occur, resulting in a non-performing fire sprinkler system.
According to a manufacturer of CPVC piping, for every 25 degree F (13.9 degree C) rise in temperature, a 50 ft (15.2 m) pipe section will elongate 0.50 inches (12.7 mm). There are three (3) installation methods used to accommodate temperature changes. Implementing these methods prevent expansion and contraction problems associated with long, straight runs of pipe by using the expansion loop method, offset method, or change of direction method. All of these methods require additional pipe bracing so it is important to accurately anticipate the range of temperatures the sprinkler system will be exposed to under normal operating conditions for an appropriate and proper installation. The CPVC piping manufacturer can supply a list of recommended loop lengths that vary in response to the expected ranges of temperature.
It is important for existing buildings with concrete floors to determine the extent to which vertical drill-in or similar type inserts can be used, and to indicate any limitations on their use in the specifications. There are many older buildings that may not have the integrity or adequate floor thickness to accommodate the use of inserts.
A grooved pipe joint assembly contains the following elements:
- Grooved pipe.
- Coupling housing.
- Bolts and Nuts.
The coupling housing engages the grooves and gasket, encircling the pipe circumference, thereby ensuring a leak-tight seal in a joint that is self-restrained. There are two types of couplings; rigid and flexible. Rigid couplings prevent any type of movement at the joint whereas flexible couplings permit a limited amount of angular and linear movement. The water used in fire sprinkler piping is neither cold nor hot so contraction or elongation of the piping is negligible which allows the use of rigid couplings. Flexible couplings allow a limited amount of angular and linear angular movement. Rigid couplings do not allow any movement.
The benefits of grooved mechanical piping can be summarized as follows:
- Piping installation times are reduced.
- Grooved mechanical pipe joints do not require a flame or fire watch required by joining methods involving welding, brazing, or soldering. Pipe fitters can install grooved mechanical joints with no additional safety measures and minimal training. Additionally, the grooved system does not have to be dried and drained which reduces downtime.
- Grooved design permits an easier scheduled maintenance because every joint has a union, resulting in simple access.
- Coupling removal is not complicated. Removal of the housing and gasket is accomplished by loosening the bolts and nuts for maintenance. Once completed, the coupling is reassembled.
- The system can be pressurized and depressurized repeatedly without fatiguing the gasket.
- Flexible couplings, if used, allow angular flexibility for use in seismic swing joints.
Editing of Section 210500 is designed to start in PART 2, progress to PART 3, and finish up with PART 1.
The various piping materials used in buried and above ground applications including pipe sleeves, sleeve-seal systems, escutcheons, pipe hangers, pipe supports, and mechanical couplings comprise the main paragraphs in PART 2. When a particular item is chosen in the inclusive choice option in PART 1 under SECTION INCLUDES, the corresponding paragraph under PART 2.01 FIRE PROTECTION SYSTEMS is activated. Related articles and optional text in PARTS 1 and 3 will be activated as well.
When a particular article or paragraph in PART 2 and PART 3 that contains a reference standard is chosen, the corresponding standard cited under REFERENCE STANDARDS in PART 1 is activated. If the Consolidated List of Citations option is active, cross sectional links (not visible in the links window) will activate the reference standard in Section 014219 – Reference Standards as well.
When a particular article or paragraph in PART 2 and PART 3 that cites another section is chosen, the corresponding Section listed under PART 1 – RELATED REQUIREMENTS is activated. Certain Sections listed under PART 1 – RELATED REQUIREMENTS are not cited in either PART 2 or PART 3 but are listed under RELATED REQUIREMENTS because they include items that might be expected to be found within this Section or include action items important for the completion of the work that are not specified in an obvious location (e.g. isn’t obvious from the section title).
All optional text and choices under PART 2 include a fill-in to accommodate any updates that listed manufacturers may offer but are not shown in the choice options. Default options for choices are based upon what would be reasonable for the application. The content of PART 2, including the choices, has been structured to accommodate listed manufacturers.