Proco - Model Style RE-231 - Eccentric Single Wide-Arch Expansion Joint
Proco Style RE-231 wide arch expansion joints are built to withstand even the most rigorous piping system configurations. They allow for axial compression or axial extension, and lateral deflection as well as angular and torsional movements.
Some of the notable features and benefits of the Proco Style RE-231 are:
- Absorption of Directional Movement
- Reduced Turbulence or Material Entrapment
- Absorption of Vibration, Noise and Shock
- Compensation for Misalignment
- Wide Service Range and Lighter Weight
A control rod unit consists of limit rods, tie rods, or compression sleeves, and a control unit assembly is a system of two or more control rod units placed across an expansion joint from flange to flange. Their purpose is to minimize possible damage caused by possible excessive motion of a pipeline. Control unit assemblies can be set at the maximum allowable expansion and / or contraction of the rubber expansion joint.
When used properly, control unit assemblies serve as additional safety enhancements, and can minimize possible damage due to adjacent equipment.
Rubber expansion joints should be installed between two fixed anchor points in a piping system. When proper anchoring can’t be provided, control units are required.When an un-anchored piping system is encountered, nuts should be tightened securely against the rod plate, to prevent over-extension due to pressure thrust caused by the expansion joint.
Listed below are three control unit configurations supplied by Proco, that are commonly used with rubber expansion joints in piping systems.
- Figure 1: Limit Rod. A limit rod control unit configuration will allow an expansion joint to lengthen to a predetermined extension setting. Spherical washers can also be furnished, upon request, to prevent any “nut to plate” binding during offset.
- Figure 2: Limit / Control Rod. This type of configuration is used to allow specified pipe expansion (expansion joint axial compression) and pipe contraction (expansion joint axial extension) movements. Spherical washers can also be furnished, upon request, to prevent any “nut to plate” binding during offset.
- Figure 3: Compression Sleeve. A compression sleeve configuration is used to allow for specified pipe expansion (expansion joint axial compression) and pipe contraction (expansion joint extension) movements. Proco will supply each compression sleeve equipped to prevent any axial movement, unless otherwise specified at the time of purchase. Spherical washers can also be furnished, upon request, to prevent any “nut to plate” binding during offset.
Absorbs Directional Movement
Thermal movements appear in any rigid pipe system due to temperature changes. The Style RC 231 and RE 231 wide arch joints allow for axial compression or axial extension, lateral deflection as well as angular and torsional movements. (Note: Rated movements in this publication are based on one plane movements.
Multiple movement conditions are based on a multiple movement calculation. Contact Proco for information when designing multiple pipe movements.)
Less Turbulence or Material Entrapment
The Style RC 231 and RE 231 expansion joints are manufactured with the integral rubber flange joining the body at a true 90° angle. This ensures the product will install snug against the mating pipe flange free of voids creating less turbulence in the pipe system. For applications where 20% or more solids are present, use the filled arch RCFA 231 and REFA 231 expansion joints for smooth bore transition with no possibility for material entrapment.
Absorbs Vibration, Noise and Shock
The Proco Style RC 231 and RE 231 rubber expansion joints effectively dampen and insulate downstream piping against the transmission of noise and vibration generated by mechanical equipment. Noise and vibrations caused by equipment can cause stress in pipe, pipe guides, anchors and other equipment downstream. The Style RC 231 and RE 231 expansion joints will help relieve noise and vibration occurrences in a pipe system. Water hammer and pumping impulses can also cause strain, stress or shock to a piping system. Install the Style RC 231 and RE 231 to help compensate for these system pressure spikes.
Compensates for Misalignment
Rubber expansion joints are commonly used by contractors and plant personnel to allow for slight pipe misalignment during installation of new piping and or replacement applications. (Although rubber expansion joints can be made with permanent offsets, it is suggested that piping misalignments be limited to no more than 1/2 the rated catalog movement. Contact Proco for resultant movement capability.)
Wide Service Range and Less Weight
Engineered to operate up to 200 PSIG (nominal size dependent) or up to 250°F (elastomer dependent), the Series RC 231 and RE 231 can be specified for a wide range of piping system requirements. The Series RC 231 and RE 231 rubber expansion joints are constructed in various elastomers with rubber impregnated polyester tire cord and ASTM wire to make up the pressure restraining member. This lightweight design installs easily and costs less to ship.
dates and elastomer designations. All Neoprene Tube/Neoprene Cover (NN) and Nitrile Tube/Neoprene Cover (NP)elastomer designated joints meet the Coast Guard Requirements and conform to ASTM F 1123-87.
Proco Products, Inc. maintains one of the largest inventories of rubber expansion joints in the world.
- A - Retaining Ring Thickness.
- B - Rubber Flange Thickness.
- C - Adjacent Mating Flange Thickness (By Others).
- D - Control Unit Plate Thickness.
- E - Double Nut Thickness is determined by Control Rod Diameter.
- F - Control Rod Bolt Length is determined by A through E + OAL 1.
- G - Control Rod Plate O.D.
- H - Maximum Rod Diameter.
Use of Control Units with Rubber Expansion Joints
A control unit assembly is a system of two or more control rod units (limit rods) placed across an expansion joint from flange to flange to minimize possible damage caused by excessive motion of a pipeline. The control unit assemblies can be set at the maximum allowable expansion and/or contraction of the rubber expansion joint. When used in this manner, control units are an additional safety factor and can minimize possible damage to adjacent equipment.
Rubber expansion joints should be installed between two fixed anchor points in a piping system. The pipe system must be rigidly anchored on both sides of the expansion joint to control expansion or contraction of the line. Piping anchors must be capable of withstanding the line thrusts generated by internal pressure or wide temperature fluctuations.
When proper anchoring cannot be provided, CONTROL UNITS ARE REQUIRED. For un-anchored piping systems nuts shall be tightened snug against rod plate to prevent over extension due to pressure thrust created by an expansion joint. Refer to “Thrust Factor in Table 2, 3, and 4 note 5 in this manual.
Known as a LIMIT ROD, this control unit configuration will allow an expansion joint to extend to a predetermined extension setting. Nuts shall be field set to no more than the maximum allowable extension movement of a rubber expansion joint (unless used in an un-anchored system). Refer to Table 2 in this manual for allowable movement capabilities. Spherical washers can also be furnished (upon request) to combat any “nut to plate” binding during offset. Consult the systems engineer for proper nut settings prior to system operation.
Important Control Unit Considerations
The number of rods, control rod diameters and control rod plate thicknesses are important considerations when specifying control units for an application. As a minimum, specifying engineers or purchasers shall follow the guidelines as set forth in Appendix C of the Fluid Sealing Association’s Technical Handbook, Seventh Edition. PROCO engineers its control unit assemblies to system requirements. Our designs incorporate an allowable stress of 65% of material yield for each rod and plate (rod and plate material to be specified by purchaser). Therefore, it is important to provide pressure and temperature ratings to PROCO when requesting control units for rubber expansion joints. It is also important to provide adjacent mating flange thickness or mating specifications to ensure correct rod lengths are provided.
- Assemble expansion joint between pipe flanges in its manufactured face-to-face length. Install the retaining rings furnished with the expansion joint.
- Assemble control rod plates behind pipe flanges as shown. Flange bolts or all thread studs through the control rod plate must be longer to accommodate the plate thickness. Control rod plates should be equally spaced around the flange. Depending upon the size and pressure rating of the system, 2, 3, 4, or more control/limit rods may be required. Refer to Table 4 in this manual or to the Fluid Sealing Association’s Technical Handbook, Seventh Edition, for control rod pressure ratings.
- Insert control/limit rods through top plate holes. Steel flat washers are to be positioned at outer plate surface.
- If a single nut per unit is furnished, position this nut so that there is a gap between the nut and the steel flat washer. This gap is equal to the joint’s maximum extension (commencing with the nominal face-to-face length). To lock this nut in position, either “stake” the thread in two places or tack weld the nut to the rod. If two nuts are supplied, the nuts will create a “jamming” effect to prevent loosening. (Nuts should be snug against flat washer and control rod plate when piping system is un-anchored.)
- Note: Consult the manufacturer if there are any questions as to the rated compression and elongation. These two dimensions are critical in setting the nuts and sizing the compression pipe sleeve (if supplied).
- If there is a requirement for compression pipe sleeves, ordinary pipe may be used, sized in length to allow the joint to be compressed to its normal limit.
- If there is a requirement for optional spherical washers, these washers are to be positioned at outer plate surface and backed up by movable double nuts.
1. Service Conditions:
Make sure the expansion joint rating for temperature, pressure, vacuum and movements match the system requirements. Contact the manufacturer for advice if the system requirements exceed those of the expansion joint selected. Check to make sure the elastomer selected is chemically compatible with the process fluid or gas.
Expansion joints are normally not designed to make up for piping misalignment errors. Piping should be lined up within 1/8”. Misalignment reduces the rated movements of the expansion joint and can induce severe stress and reduce service life. Pipe guides should be installed to keep the pipe aligned and to prevent undue displacement.
Solid anchoring is required wherever the pipeline changes direction and expansion joints should be located as close as possible to anchor points. If piping is not adequately anchored, control rods should be used. If anchors are not used, pressure thrust may cause excessive movement damaging the expansion joint.
4. Pipe Support:
Piping must be supported by hangers or anchors so expansion joints do not carry any pipe weight.
5. Mating Flanges:
Install the expansion joint against the mating pipe flanges and install bolts so that the bolt head and washer are against the retaining rings. If washers are not used, flange leakage can result – particularly at the split in the retaining rings. Flange-to-flange dimension of the expansion joint must match the breech opening. Make sure the mating flanges are clean and are flat faced type or no more than 1/16” raised face type. Never install expansion joints that utilize split retaining rings next to wafer type check or butterfly valves. Serious damage can result to a rubber joint of this type unless installed against full face flanges.
6. Bolting Torque:
Table 7 shows the recommended torque ranges for non-metallic expansion joints with full-faced rubber flanges: Torque specifications are approximate. Tighten bolts in stages using cross-bolt tightening pattern. If the joint has integral fabric and rubber flanges, the bolts should be tight enough to make the rubber flange OD bulge between the retaining rings and the mating flange. After installation, the system should be pressurized and examined to confirm a proper seal. Torque bolts sufficiently to assure leak-free operation at hydrostatic test pressure. Note: Torque values are approximate due to mating flange surfaces, installation offsets, operating pressures and environmental conditions.
Ideal storage is in a warehouse with a relatively dry, cool location. Store flanges face down on a pallet or wooden platform. Do not store other heavy items on top of expansion joints. Ten year shelf life can be expected with ideal conditions. If storage must be outdoors, place on wooden platform and joints should not be in contact with the ground. Cover with a tarpaulin.
8. Large Joint Handling:
Do not lift with ropes or bars through the bolt holes. If lifting through the bore, use padding or a saddle to distribute the weight. Make sure cables or forklift tines do not contact the rubber. Do not let expansion joints sit vertically on the edges of the flanges for any period of time.
9. Additional Tips:
A. Do not insulate over a non-metallic expansion joint; however, if insulation is required, it should be made removable to permit easy access to the flanges. This facilitates periodic inspection of the tightness of the joint bolting.
B. It is acceptable (but not necessary) to lubricate the expansion joint flanges with a thin film of graphite dispersed in glycerin or water to ease disassembly at a later time.
C. Do not weld in the near vicinity of a non-metallic joint.
D. If expansion joints are to be installed underground, or will be submerged in water, contact manufacturer for specific recommendations.
E. If the expansion joint will be installed outdoors, make sure the cover material will withstand ozone, sunlight, etc.
F. Check the tightness of lead-free flanges two or three weeks after installation and retighten if necessary.
Warning: Expansion joints may operate in pipelines or equipment carrying fluids and/or gasses at elevated temperature and pressures and may transport hazardous materials. Precautions should be taken to protect personnel in the event of leakage or splash. Rubber joints should not be installed in areas where inspection is impossible. Make sure proper drainage is available in the event of leakage when operating personnel are not available.
Anchored System Note:
Although limit rods are not required in an anchored pipe system, you may want to consider using them. If an anchor were to fail, the limit rods would be capable of handling the pressure thrust of the system and lessen the likelihood of an expansion joint failure.
Un-Anchored System Note:
Rod sets should be installed so that external nuts are snug against the plate at installation. Pressure thrust of the pipe system can cause expansion joint to over-elongate and reduce movement capabilities.