Repair of TubeTubesheet Weld Cracks in a Cracked Gas/Steam Heat Exchanger. improper tube expansion, abnormal clearance between tube The tube-to-tubesheet joint 3-D finite element analysis of roller-expanded heat Repeated de-stubbing and re-tubing of heat exchangers in petrochemical plants during their useful lifetime may result in over-enlarged tubesheet holes with overtolerances that exceed those prescribed by Tubular Exchanger Manufacturing Association (TEMA) standards (1988). Roller expansion of tubes in these over-enlarged holes may result in tube thinning and weakening of the joint due to a
(1988). Roller expansion of tubes in these over-enlarged holes may result in tube thinning and weakening of the joint due to a decrease of interfacial pressure between the tube and tubesheet. In the present work, a 3-D nite ele-ment (FE) model of a tube-tubesheet joint was used to determine displacement and stress distributions along the Assuring Tube-to-Tubesheet Joint Tightness and Strength Effective Expansion and Repair of Tube-to-Tubesheet Joints in a High Pressure Feedwater Heater POWER2010 Weld Rod Fatigue Analysis Using Effective Notch Stress Method Copper Nickel :Sea Water System ComponentsOften the easiest and least expensive method is to mechanically expand the tube into the drilled hole in the tubesheet usually by roller expansion. Ideally the tubesheet should be harder than the tubes. A mechanically expanded joint may be acceptable when :Service
Correct Expansion. Percentage wall reduction is the most frequently used procedure to obtain the optimal mechanical joint between a Tube and Tube Sheet. This length must be at least 1/4 shorter than the effective length of the 2R roll. Effectively Design Shell-and-Tube Heat Exchangersployed, xed-tubesheet construction may be selected for fouling services on the shellside. In the event of a large differential temperature between the tubes and the shell, the tubesheets will be un-able to absorb the differential stress, thereby making it necessary to incor-porate an expansion joint. This takes away the advantage of low cost Effects of friction on roller expanded tubetubesheet An experimental study has been conducted to evaluate the effect of roller expansion of heat exchanger tubes in enlarged tubesheet holes on joint strength, tube wall reduction (i.e., thinning), and
Perma Tube Plugs install in minutes, and their broad expansion range fits multiple gauges reducing inventory and costs. Controlled and repeatable installation minimizes installer fatigue and protects against damage to tubesheet ligaments and adjacent tubesheet joints, extending the life of heat exchangers and reducing costs for retubing. Heat Transfer by Heat Exchangers Tubes and TubesheetTube sheet materials range as tube materials. Tubes are attached to the tube sheet by pneumatic or hydraulic pressure or by roller expansion. Tube holes can be drilled and reamed and can be machined with one or more grooves. This greatly increases the strength of the tube joint. Repair of Exchanger tubes according to ASME PCC-2Tubeside Repair by Plugging ASME PCC-2. Repair of tubes may be accomplished by plugging the tube at the tubesheet with a welded or mechanical attachment. All tubes that are plugged should be pierced to provide for venting and draining. Piercing of each tube prevents possible plug blowout and permits the validation of the integrity of the tube plug.
Feb 10, 2004 · Differential thermal expansion can result with thicker tube sheets. When the expansion due to heat varies noticeably between the thinner tube and tube sheet, a shift of the tube results. One of the most important steps for ensuring a safe and permanent tube joint is to thoroughly clean the surfaces of the tube end and the tube hole wall. TUBE-TO-TUBESHEET JOINTS:THE MANY CHOICES welding. Tube end expansion may be done either by hydraulic means or by use of a conventional three roller expander. Welding may be done manually, with or without filler metal, or by use of semiautomatic welding equipment. Before the fabrication step is begun, a mock-up tube-to-tubesheet joint should be assembled using the Tube to Tube sheet welding - Boiler and Pressure Vessel Nov 09, 2005 · Radiography of tube to tube sheet joint is not practical and I have never seen this requirement even for heat exchangers with very high pressure and temperature on tube side. Radiography of tube to tube sheet weld is only recommended where the tubes are butt welded at shell side face of tube sheets .
Post expansion C o n t a c t P r e s s u r e (M P a) EX-82-1 Yield 52 ksi Without Tubesheet Bowing Zero Crevice Pressure 7/8"-diameter tube, hydraulic expansion pressure=34 ksi Max 1 ksi difference during NO, negligible difference during MSLB. Tube-to-Tubesheet Joint LeakagePost expansion C o n t a c t P r e s s u r e (M P a) EX-82-1 Yield 52 ksi Without Tubesheet Bowing Zero Crevice Pressure 7/8"-diameter tube, hydraulic expansion pressure=34 ksi Max 1 ksi difference during NO, negligible difference during MSLB. YIMPACT - Explosive Engineering, Welding & Expansion TEiYIMPACT explosive expansion provides an effective alternative to the fabrication of high integrity mechanical tube / tubesheet joints for many heat exchanger designs and tube / tubesheet problems. Multiple detonations of pre-engineered explosive charges, designed for specific tube / tubesheet material and size combinations enable tubes to be
hydraulic expansion yields consistent joints throughout the tubesheet. The system is easy to operate with minimal training and the method has been applied successfully to expand tubes into tubesheets as thin as ¾ up to as thick as 33. Water pressure is applied to the tube ID over the full length of the joint