Series SCR & SAB Seismic Restraints

Transcription

1 Bulletin No.SRM/2000 Series SCR & SAB Seismic Restraints Seismic Braces for Piping, Ductwork, Conduit, and Equipment

2 VMC Seismic cable restraints (SCR) and single arm braces (SAB) are an excellent means to restrain suspended equipment, piping, duct and electrical cable trays during an earthquake. With isolated systems, seismic cables are required. The cables are installed slightly slack so as to avoid short-circuiting the isolation system. The VMC seismic cable restraints come in kit form to minimize labor cost for the contractor. Each pre-packaged kit contains all of the necessary hardware for proper installation and positive attachment to the building structure. Our cables are factory swaged on one end to eliminate extra installation time. Seismic cable kits are made from 7 x 19 aircraft cable and are available in 1/8",1/4", and 3/8" sizes. Non-isolated systems can utilize our single arm brace. Our SAB series brackets allow for positive seismic attachment of all suspended systems. The bracket design accepts field-supplied unistrut or steel angle and allows for a full range of motion in all directions for ease of installation. The SAB-1 is designed for steel attachment, and the SAB-2 is utilized when concrete is the anchoring medium. Both the VMC Series SCR and Series SAB strictly comply with all requirements of the national building codes and the International Building Code (IBC 2000). 1. W = Weight at Center of Gravity 2. fp = Horizontal force by code = "g" x W 3. P Cable = fp = Force on cable or brace Cos45 Throughout this brochure, you will find graphs and charts which are to be used as guidelines only. Many different installation configurations are possible which may effect the performance of the restraints used. As a basic rule of thumb, the force acting on the seismic cable restraint or single arm brace can be broken down into a static analysis for selection purposes. Looking at suspended pipe, duct, cable tray or equipment, you will notice that the seismic restraint is positioned at an angle of approximately 45 up from the point of support. To determine the approximate seismic load imparted on the restraint: 1. Determine weight of the equipment, pipe, or duct to be restrained. 2. Multiply the weight by the seismic acceleration specified by code to determine horizontal seismic force. 3. Solve for force on seismic cable or brace by dividing the horizontal seismic force by Cos45. 2

3 Type SCR Seismic Cable Restraints Each Kit consists of: 2 - lengths of cable - swaged one end -11 ft. long or 20 ft. long, 7 x 19 Galvanized Aircraft Cable, 1/8", 1/4", 3/8" dia. 2 - concrete angle brackets 4 - shackles 2 - thimbles 4 - U-bolts 2 - clevis angles Seismic Load Table Wire Recommended Max. Equipment Mimimum Recommended Rope Dia. Working Load Weight Concrete Anchor (2) in. lbs..5g 1g Dia. (in.) Embedment Cable Spacing Guide -.5 "G" Cable Size and Spacing Pipe Size 1/8" 1/4" 3/8" T* - L* T* - L* T* - L* ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft. 12 N/A ft t. 14 N/A ft ft. 16 N/A ft ft. 18 N/A ft ft. *T = *L = Cable Spacing Guide - 1 "G" Cable Size and Spacing Pipe Size 1/8" 1/4" 3/8" T* - L* T* - L* T* - L* ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft. 8 N/A ft ft. 10 N/A ft ft. 12 N/A ft ft. 14 N/A ft ft. 16 N/A ft ft. 18 N/A N/A ft. *T = *L = Project: Architect: Acoustician Contractor: Project No. Date: Drawing No. VIBRATION MOUNTINGS & CONTROLS, INC. An Aeroflex, Inc. Company 113 Main St. Box 270, Bloomingdale, NJ Toll Free: LOW-VIBE Tel: 973/ Fax: 973/ TYPE "SCR " SEISMIC RESTRAINTS 3

4 Single Arm Brace Type SAB SAB-1 for equipment and steel structure attachment SAB-2 for concrete anchorage 9 16" holes for 1 2" bolt 13 16" hole for 3 4" bolt 9 16" hole (1 2" concrete anchors) 2 places 8" 6" 9 16" holes for 1 2" bolt (6 places) 2 3 4" 4" 1 1 2" 4" 1 1 2" 2 3 4" Single Arm Brace Spacing Guide -.5 "G" Pipe Size Spacing T - L ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft. *T = *L = Single Arm Brace Spacing Guide - 1 "G" Pipe Size Spacing T - L ft ft ft ft ft ft ft ft ft ft ft ft ft ft. 18 N/A *T = *L = SAB brackets have been designed to accept field-supplied unistrut or steel angle as the rigid brace. Two brackets are required per brace. Model SAB-1 is used at the equipment, pipe, or duct and at the building structure when attaching to steel. When bolting the brace into concrete building structure, SAB-2 must be utilized. (SAB-1 at equipment, SAB-2 at structure). Project: Architect: Acoustician Contractor: Project No. Date: Drawing No. VIBRATION MOUNTINGS & CONTROLS, INC. An Aeroflex, Inc. Company 113 Main St. Box 270, Bloomingdale, NJ Toll Free: LOW-VIBE Tel: 973/ Fax: 973/ TYPE "SAB" SEISMIC RESTRAINTS 4

5 Isolated Piping Anchor Bolts by others Building Structure Concrete Angle Bracket Shackle Thimble VMC Type RSH Vibration Hanger U-bolt 7 x 19 Aircraft Cable VMC Series SRBC Seismic Rod Clamp Each Cable Kit consists of: 2 - lengths of cable - swaged one end 2 - concrete angle brackets 4 - shackles 2 - thimbles 4 - U-bolts 2 - clevis angles Clevis Angle Bracket 45 VMC Series SCR Seismic Cable Restraint Typical Brace (1 SCR Kit) Pipe Clevis (secondary pipe clamp must be used for longitudinal brace) / / Piping must be positively attached to the structure of the building in case of an earthquake. Typically, pipe is suspended on vibration isolation hangers within mechanical equipment rooms, or within 50 feet of vibrating equipment, whichever is greater. This isolated piping must also be seismically restrained to the building structure without compromising the vibration isolation (also known as "short circuiting"). A "run" of pipe must be restrained both longitudinally (in the direction of its run) and transversely (perpendicular to its run) to insure that it moves with the building and remains attached to it during an earthquake. Restraining the isolated pipe is accomplished by utilizing the VMC series SCR seismic cable restraints. Our seismic cable restraints insure positive attachment to the pipe supports, and when installed slightly slack, do not compromise the vibration isolation by short-circuiting the spring hanger. Our cable kits come with 2 lengths of cable, swaged on one end, and all of the necessary hardware for easy installation by the contractor. VMC Seismic cable restraints are a required component when restraining isolated pipe. TYPE SCR BRACING SCHEMATIC 5

6 Non-Isolated Piping SAB-2 required for concrete attachment. SAB-1 may be used for steel attachment VMC Series SRBC Seismic Rod Bracing Clamp VMC Series SAB-2 Anchor bolts by others (minimum of 2 for concrete attachment) Non-isolated threaded rod Brace (requires additional pipe clamp at clevis not shown) Brace Unistrut or angle steel (by others) VMC Series SAB-1 Clevis Hanger (pipe clamp must be used for longitudinal restraint capability) / / TYPE SAB BRACING SCHEMATIC Non-isolated piping has the same bracing requirements as isolated piping. However, piping that is rigidly supported without isolators can be seismically restrained using the VMC series SAB Single Arm Brace. Our rigid single arm brace consists of two brackets, which allow the brace a full range of motion for ease of installation. The bracing material (typically unistrut or angle steel) is contractor supplied and cut to size in the field. The brace brackets are available in two sizes and incorporate properly sized and spaced anchor bolt holes. The SAB-1 is designed for attachment to the pipe hanger and anchoring into steel. The SAB-2 incorporates two anchor bolt holes for attachment to concrete. Unlike cable restraints, which require 2 cables per brace location, the SAB series requires only one brace per transverse location and one brace per longitudinal location. An example on ordering the SAB series is as follows: brace anchored into concrete requires: 1 pc SAB-1 (for the attachment at the pipe hanger) 1 pc SAB-2 (for the attachment of the brace to the concrete ceiling) OR brace anchored into steel requires: 2 pcs SAB-1 (1 pc for attachment to the pipe hanger, 1 pc for attachment to the steel structure) 6

7 Isolated Suspended Equipment NOTE: Equipment must be positively attached to support steel VMC Type RSH Hanger VMC Series SCR (2 kits required per piece of equipment) Hanger Rods (by others) Support Steel (by others) All suspended mechanical equipment must be seismically restrained. While floor mounted equipment typically utilizes a seismically rated vibration isolator or separate snubber, no such device exists for suspended equipment. This is because suspended equipment can have any number of possible elevations. Fortunately, it is possible to seismically restrain isolated suspended equipment by using VMC Series SCR Seismic Cable Restraints. Series SCR cable restraints are required for externally isolated equipment only. Each piece of equipment requires a minimum of 4 cables, (2 SCR kits) installed slightly slack to insure continuity of the vibration isolation system. The cables are installed at 45 from the horizontal plane of the equipment, and in plan view, 45 from each corner. The diameter of the cable is determined through calculation and is based on the weight of the equipment and specified seismic force. Seismic Load Table Wire Recommended Max. Equipment Mimimum Recommended Rope Dia. Working Load Weight Concrete Anchor (2) in. lbs..5g 1g Dia. (in.) Embedment

8 Non-Isolated Suspended Equipment Threaded Rod (by others) Plan View Structural Steel (by others) VMC SAB-1 VMC SAB-2 Non-isolated or internally isolated suspended equipment can be seismically restrained utilizing the VMC Series SAB Single Arm Brace. Any internal isolation must have its own seismic capability certified by the unit manufacturer. While externally isolated suspended equipment requires a minimum of 4 cables, the SAB series brace can use as few as two braces per application. The braces are installed at 45 up from the horizontal plane of the equipment, and perpendicular to each other at either end of the equipment. Brace (unistrut by others) VMC SAB-1 Electrical Cable Trays VMC SAB-2 Cable Tray VMC SAB-2 VMC SAB-1 Brace (unistrut by others) The electrical system in a building is perhaps the most important part of the HVAC system. Should the power be interrupted due to inadequately restrained electrical systems, the HVAC system will be rendered inoperable, and the building useless. While we typically take great strides to insure that the mechanical equipment, pipe and ductwork are properly restrained, the electrical system is often overlooked. Any electrical conduit, cable trays, etc. used to supply power to the HVAC or emergency backup systems must be properly restrained using the VMC Series SAB Single Arm Brace. 8

9 Isolated Ductwork Concrete Angle Bracket Anchor Bolts (by others) Building Structure Shackle VMC Type RSH Vibration Hangers U-bolts Thimble Each Kit consists of: 2 - lengths of cable - swaged one end -11 ft. long or 20 ft. long, 7 x 19 Galvanized Aircraft Cable, 1/8", 1/4", 3/8" dia. 2 - concrete angle brackets 4 - shackles 2 - thimbles 4 - U-bolts 2 - clevis angles Duct: (6 square feet and larger requires restraint) Lower Angle Bracket / / Ductwork must be positively attached to the structure of the building in case of an earthquake. Isolated duct must be seismically restrained to the building structure without compromising the vibration isolation (also known as "short circuiting"). A "run" of duct must be restrained both longitudinally (in the direction of its run) and transversely (perpendicular to its run) to insure that it moves with the building and remains attached to it during an earthquake. Restraining the isolated duct is accomplished by utilizing the VMC series SCR seismic cable restraints. Our seismic cable restraints insure positive attachment to the ductwork, and when installed slightly slack, do not compromise the vibration isolation by short-circuiting the spring hanger. Our cable kits come with 2 lengths of cable, swaged on one end, and all of the hardware shown above for easy installation by the contractor. VMC Seismic cable restraints are a required component when restraining isolated duct. SCR BRACING SCHEMATIC 9

10 Non-Isolated Duct Work Anchor bolts (by others) Non-isolated threaded rod brace (unistrut by others) SAB-2 required for attachment to concrete. SAB-1 may be used for attachment to steel brace (unistrut by others) Duct: (6 square feet and larger requires restraint) SAB-1 / / TYPE SAB BRACING SCHEMATIC Non-isolated duct has the same bracing requirements as isolated duct. However, duct that is rigidly supported without isolators can be seismically restrained using the VMC series SAB Single Arm Brace. Our rigid single arm brace consists of two brackets, which allow the brace a full range of motion for ease of installation. The bracing material (typically unistrut or angle steel) is contractor supplied and cut to size in the field. The brace brackets are available in two sizes and incorporate properly sized and spaced anchor bolt holes. The SAB-1 is designed for attachment to the ductwork and anchoring into steel. The SAB-2 incorporates two anchor bolt holes for attachment to concrete. Unlike cable restraints, which require 2 cables per brace location, the SAB series requires only one brace per transverse location and one brace per longitudinal location. An example on ordering the SAB series is as follows: brace anchored into concrete requires: 1 pc SAB-1 (for the attachment at the duct) 1 pc SAB-2 (for the attachment of the brace to the concrete ceiling) OR brace anchored into steel requires: 2 pcs SAB-1 (1 pc for attachment to the duct, 1 pc for attachment to the steel structure) 10

11 Seismic Rod Bracing Clamp SRBC Rod Bracing Clamp Seismic forces act in all directions. Because the threaded rod is sized purely for gravity loads, it is necessary to add additional rod bracing to prevent buckling. Uplift forces can easily exceed the dead load on the rod resulting in compressive forces. If un-braced the rod can buckle and fail. With the addition of the VMC series SRBC bracing clamp, angle steel bracing can be quickly and easily added to the rod, stiffening and strengthening it. When vibration hangers are utilized, VMC recommends attaching the hanger directly to the overhead structure and adding an uplift washer under the box to prevent the spring from becoming unloaded. Clamp Sizing Table: Used with Size Angle Size Hanger Rod Sizes SRBC " x 1" x 1 4" 3 8", 1 2", 5 8" SRBC " x 1 1 2" x 1 4" 3 4", 7 8", 1", 1 1 8" Note: Three clamps are required per rod. Clamps are furnished complete with bolt and nut as illustrated. Project: Architect: Acoustician Contractor: Project No. Date: Drawing No. VIBRATION MOUNTINGS & CONTROLS, INC. An Aeroflex, Inc. Company 113 Main St. Box 270, Bloomingdale, NJ Toll Free: LOW-VIBE Tel: 973/ Fax: 973/ TYPE "SCR " SEISMIC RESTRAINTS 11

12 Vibration Mountings & Controls, Inc. An Aeroflex, Inc. Company 113 Main Street, Box 270, Bloomingdale, NJ Tel: 973/ TOLL FREE: LOW-VIBE Fax: 973/ Vibration Mountings & Controls, Inc. 5M 4/2000