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CONSTRUCTION TECHNOLOGY CARD
Специализированные работы (сантехника, электрика, вентиляция, сварка)

Construction Technology Card: Mechanized Flux-Cored Arc Welding of Reinforcing Bar Extensions in Reusable Molds

This construction technology card regulates the processes of mechanized flux-cored arc welding in reusable molds for horizontal and vertical connections of reinforcing bar extensions. The document establishes engineering requirements for preparation, assembly, welding parameters, and quality control of connection joints in precast concrete structures.
6 sections 18 figures

Materials

  • Gas-shielded/self-shielded flux-cored wire for mechanized welding (Ø 2.6 - 3.0 mm, yield strength of deposited metal ≥ 500 MPa)
  • Basic-coated welding electrodes (type E7018 / E50A, Ø 4.0 mm)
  • Heat-resistant fibrous sealing cord (operating temperature up to 1000 °C)
  • Graphite or copper reusable molds (corresponding to diameters 16-40 mm)
  • Temperature-indicating crayons (for temperature control at 200 °C, 250 °C, 600 °C)
  • Technical oxygen and propane-butane mixture for oxy-fuel processing

Equipment

  • Industrial-grade semi-automatic welding machine with wire feeder (current up to 500 A)
  • Welding rectifier (DC power source with drooping/flat V-A characteristic, 500 A)
  • Portable drying oven for baking welding materials (heating up to 400 °C)
  • Equipment set for gas cutting and heating (torches, gas burners, regulators, cylinders)
  • Ultrasonic flaw detector with angle beam probes for testing rebar joints
  • Quick-release clamps and screw clamps for mold fixation
  • Angle grinder with abrasive wheels
1

1. Scope of Application and General Organizational Requirements

This technology is applied for the construction of rigid connection joints (beam-to-column, column-to-column) in multi-story precast concrete frame buildings. The concrete strength of the joined elements must comply with the design classes (C20/25 – C40/50 according to international classification). The technology is designed for welding single and paired reinforcing bar extensions with a diameter from 16 to 40 mm, with a yield strength of 400-500 MPa (corresponds to classes B500B / Grade 60 or 35GS/25G2S steel).

Only engineers with specialized education in welding production, certified according to the requirements of ISO 14731 or equivalent standards, are permitted to supervise welding operations. The direct execution of connections is entrusted to welders holding valid qualification certificates for mechanized submerged arc or flux-cored arc welding.

Before starting work, the installation level must be equipped with calibrated equipment. The welder's workstation must be reliably protected from atmospheric precipitation and wind loads. When working at heights of more than 1.3 m, the use of reusable scaffolding platforms with non-combustible decking and the use of fall arrest systems are mandatory.

Fig. 1 — Geometric parameters and rib configuration of deformed reinforcing bars
Fig. 1 — Geometric parameters and rib configuration of deformed reinforcing bars
1Upper deformed reinforcing bar segment showing transverse ribs for enhanced concrete bonding
2Lower deformed reinforcing bar segment illustrating an alternative rib pattern or orientation
3Transverse rib spacing (pitch), denoted as l1 in the original, representing the distance between consecutive ribs
4Inclination angle of the transverse ribs relative to the longitudinal axis on the left side, denoted as alpha 2
5Inclination angle of the transverse ribs relative to the longitudinal axis on the right side, denoted as alpha 1
6Nominal diameter (d_H) of the upper reinforcing bar, indicating the overall cross-sectional size
7Nominal diameter (d_H) of the lower reinforcing bar, consistent with the upper bar for structural uniformity
8Inclination angle of the transverse ribs relative to the longitudinal axis for the lower bar segment, denoted as alpha 1
  1. Staffing the site with qualified personnel and calibrated equipment.
  2. Installation of barriers and shelters in the installation zone to protect the weld pool from wind and precipitation.
  3. Setup of safe working platforms at height using non-combustible materials.
2

2. Preparation and Alignment of Reinforcing Bar Extensions

Geometric parameters and the relative position of reinforcing bars must strictly comply with the working drawings. The allowable misalignment for reinforcement with a diameter of 16-28 mm is no more than 15% of the nominal diameter, and for diameters of 32-40 mm — no more than 10%. The angular deviation of the joined bar axes must not exceed 3°. The minimum length of the clear extension from the concrete body must be 150 mm.

The alignment of the bars to a coaxial position is carried out by thermal straightening. Heating is performed with a gas torch to a temperature of 600-800 °C (visually — to a dark cherry color). To avoid thermal damage to the concrete and loss of its strength characteristics (destruction of the cement paste), the heating zone must be located at a distance of no closer than 70 mm from the end of the concrete element.

The rebar ends are prepared exclusively by oxy-fuel cutting; cutting with an electric arc is strictly prohibited. For horizontal single joints, a bevel is formed at an angle of 10-15° with a gap of 12-20 mm. For paired horizontal bars, the angle is 12-15° (gap 12-18 mm). Vertical extensions require a bevel of 40-50°. The welding zone is cleaned with wire brushes to bare metal over a length of at least 10 mm from the ends; traces of moisture are removed by the torch flame.

Fig. 1 — Geometric parameters and profile details of a deformed reinforcing bar at a transverse intersection
Fig. 2 — Geometric parameters and profile details of a deformed reinforcing bar at a transverse intersection
1Outer diameter (dH) of the deformed reinforcing bar, measured across the extreme edges of the transverse ribs
2Gap dimension (z), defining the transverse distance from the longitudinal centerline to the start of the transverse rib profile
3Diameter (l1) of the intersecting smooth transverse wire, serving as an orthogonal structural tie or mesh component
4Angle of inclination (β1) between the transverse rib axis and the horizontal transverse wire
5Angle of inclination (α1) between the transverse rib axis and the primary longitudinal axis of the reinforcing bar
6Longitudinal rib of the reinforcing bar, formed as a continuous spine during the hot-rolling process
7Transverse rib of the reinforcing bar, designed with an inclined profile to provide mechanical anchorage and prevent slip within concrete
  1. Visual and instrumental inspection of the alignment and length of reinforcing bar extensions.
  2. Thermal straightening of the bars (heating to 600-800 °C) while maintaining a safe distance from the concrete.
  3. Oxy-fuel cutting of the ends to form standard bevel angles.
  4. Mechanical cleaning of the beveled edges and the adjacent zone (minimum 10 mm) to bare metal.
3

3. Installation of Reusable Mold Elements

To retain the molten metal of the weld pool and shape the weld geometry, split reusable molds made of graphite or copper are used. The mold consists of two symmetrical halves with a vertical parting plane, corresponding to the diameter of the reinforcement being welded. The mold is installed strictly symmetrically relative to the axis of the root gap.

A critical step is sealing the gaps between the reinforcing bar and the mold walls to prevent the leakage of liquid metal and slag, which can lead to the formation of voids and lack of fusion. Sealing is performed with a heat-resistant fibrous cord at a distance of 15-20 mm from the bar ends. The sealant material must be chemically neutral and not emit gases upon contact with the melt.

The mold halves are secured using quick-release clamps, screw clamps, or mounting brackets. The clamping force must be sufficient to prevent the mold from slipping under the influence of the weld pool mass and thermal deformations, but not cause cracking of the graphite elements. The use of fixing wedges is permitted.

Fig. 1 — Exothermic welding joint for reinforcing steel bars within a graphite mold assembly
Fig. 3 — Exothermic welding joint for reinforcing steel bars within a graphite mold assembly
1Prepared ends of the reinforcing steel bars aligned for welding
2Vertical sprue or gating system for pouring the molten exothermic material
3Upper section of the split graphite mold or crucible containing the welding reaction
4Lower section of the split graphite mold securing the reinforcing bars in position
5Solidified weld metal forming the fused joint between the two reinforcing bars
6Slag or riser material remaining in the sprue after the exothermic reaction and solidification
  1. Cleaning the internal surfaces of the reusable molds from slag and spatter of previous cycles.
  2. Symmetrical installation of the mold halves onto the prepared joint.
  3. Sealing the gaps with a heat-resistant cord in the zone 15-20 mm from the ends.
  4. Rigid fixation of the mold with clamps, checking for any play.
4

4. Welding Materials and Welding Parameters

Self-shielded or gas-shielded flux-cored wire with a diameter of 2.6–3.0 mm, intended for mechanized welding, is used as the filler material. For defect repair and tack welding, basic-coated electrodes (type E7018 according to AWS or E50A), with a diameter of 4.0 mm, are used. Repeated heat treatment (baking) of the flux-cored wire is not permitted due to the risk of destroying the flux core.

Before use, materials undergo mandatory baking: flux-cored wire is held at 160-180 °C for 1.5-2.5 hours, electrodes — at 350-400 °C for 1-2 hours. Welding materials are issued to the workstation in volumes not exceeding the requirement of one shift and are stored in moisture-protected heated quivers.

The process is carried out using direct current electrode positive (DCEP). Welding parameters are strictly regulated: for diameters of 16-25 mm, the operating current is 280-300 A at an arc voltage of 24-26 V; for diameters of 36-40 mm, the current is increased to 350-410 A at a voltage of 28-34 V. The wire feed speed is adjusted within the range of 140-250 m/h. The electrode extension length must be maintained within 30-80 mm depending on the bevel depth.

Fig. 1 — Thermit welding of reinforcing bars showing mold assembly and completed weld
Fig. 4 — Thermit welding of reinforcing bars showing mold assembly and completed weld
1Reinforcing bar (rebar) to be welded, showing ribbed surface profile
2Gap between reinforcing bars, allowing for the flow and fusion of molten weld metal
3Welding mold (typically ceramic or graphite), enclosing the joint area to contain the molten metal
4Mold cavity or sprue, where the thermit reaction occurs and molten metal is channeled
5Solidified weld metal (fused steel), forming the structural connection between the rebars
6Solidified slag, a byproduct of the thermit reaction that floats to the top of the weld pool
  1. Baking of welding materials in electric ovens according to temperature-time schedules.
  2. Setting the power source to direct current electrode positive (DCEP).
  3. Setting the current (280-410 A) and voltage (24-34 V) parameters depending on the rebar diameter.
  4. Adjusting the wire feeder to ensure a stable electrode extension (30-80 mm).
5

5. Welding Process Technology

Arc striking is performed exclusively by touching the wire to the end of the reinforcing bar extension. It is strictly forbidden to strike the arc on the elements of the reusable mold to prevent their erosion and weld contamination. When welding horizontal joints, the lower part of one end is first melted with transverse weaving motions, then the arc is transferred to the second bar. After forming a single slag and metal pool, the space is filled by fast arc movements along the edges of the pool.

For vertical joints, the arc is struck on the end of the lower extension. After the formation of the liquid metal pool, the bevel is filled by alternating weaving motions in the area of the upper bar bevel with circular motions along the mold perimeter. The wire should be fed perpendicularly to the melt surface to minimize spatter.

At sub-zero ambient temperatures, adjustments are required: for every 3 °C drop in temperature below zero, the welding current is increased by 1%. Preheating the joint to 200-250 °C over a length of 90-150 mm (controlled by temperature-indicating crayons) is mandatory. Welding at temperatures below -30 °C is prohibited. At the end of the welding process, to avoid the formation of a shrinkage cavity, 2-3 pauses of 3-4 seconds are made, moving the arc to the edges of the pool. Mold removal is done by light tapping no earlier than 5-10 minutes after the slag has crystallized.

Fig. 1 — Splicing methods for reinforcing bars: mechanical connection and molded/grouted connection
Fig. 5 — Splicing methods for reinforcing bars: mechanical connection and molded/grouted connection
1Mechanical splice or threaded connection point between two reinforcing bars
2Angled end preparation or gap between the reinforcing bars
3Mold, sleeve, or surrounding enclosure used to contain the splice or bonding material
4Seal or gasket at the base of the mold to prevent leakage of the bonding material
5Bonding material, such as grout or weld metal, filling the space between the rebar ends
6Upper level or surface of the bonding material within the mold
  1. Preheating the joint to 200-250 °C (when working in low-temperature conditions).
  2. Striking the arc on the rebar body and forming the primary weld pool.
  3. Filling the melting space with specified electrode weaving trajectories (zigzag, circular).
  4. Executing 2-3 pauses at the end of welding to prevent shrinkage cavities.
  5. Natural cooling for 5-10 minutes, mold dismantling, and slag removal.
6

6. Quality Control and Acceptance Criteria for Joints

The quality control system includes incoming, in-process, and acceptance stages. Incoming control verifies material certificates, the functionality of rectifiers, and assembly accuracy (gaps, alignment). In-process control, performed at least twice per shift, includes a visual assessment of the weld geometry, the absence of undercuts, and monitoring compliance with the welding temperature conditions.

Final acceptance is based on the results of visual-dimensional, ultrasonic, and mechanical testing. Surface defects are strictly limited: no more than 5 external pores or slag inclusions are allowed per joint, while the maximum diameter of an individual defect must not exceed 2.0 mm. Local surface defects are eliminated by grinding out with an abrasive tool followed by repair welding after preheating the zone to 200-250 °C.

Instrumental testing includes ultrasonic testing (UT) of 10% of the total volume of welded single joints. Static tensile mechanical tests are conducted on 3 control specimens from each batch. For 500 MPa class reinforcement, the arithmetic mean value of the ultimate tensile strength must be at least 586 MPa, and the lowest permissible value in the sample — not lower than 500 MPa. Joints with unacceptable internal defects must be cut out and replaced using an intermediate insert (at least 80 mm long) followed by 100% UT inspection of the new welds.

Fig. 1 — Spot welding connections for reinforcing steel bars showing end-to-end and lap joint configurations
Fig. 6 — Spot welding connections for reinforcing steel bars showing end-to-end and lap joint configurations
1Reinforcing steel bar, primary load-bearing element in tension or compression
2Spot weld, connects two reinforcing bars end-to-end, defining weld length (l)
3Reinforcing steel bar, secondary load-bearing element in tension or compression
4Weld penetration depth, indicating the extent of fusion into the base metal
5Spot weld for lap joint, connects two parallel reinforcing bars, defining weld length (l)
6Weld penetration depth in lap joint, indicating the extent of fusion into the parallel bars
7Nominal diameter of reinforcing bar (d_H), indicating the size of the rebar used in the connection
  1. 100% visual and dimensional inspection of welded joints after slag removal.
  2. Ultrasonic testing of 10% of single joints in the batch.
  3. Selection of 3 control specimens for static tensile testing in the laboratory.
  4. Local repair of surface defects (up to 2.0 mm) or complete cut-out of rejected joints.
  5. Execution of as-built documentation and placement of the welder's personal stamp.
Fig. 1 — Detail of mechanical splice interaction with deformed reinforcing bar showing key geometric parameters
Fig. 7 — Detail of mechanical splice interaction with deformed reinforcing bar showing key geometric parameters
1Deformed reinforcing bar (rebar) with transverse ribs providing bond strength in concrete
2Mechanical splice component or gripping wedge engaging with the rebar ribs
3Rib height (h1) on one side of the deformed reinforcing bar
4Rib height (h2) on the opposite side of the deformed reinforcing bar
5Interaction length (l) of the mechanical splice component over the rebar
6Nominal outer diameter (d_H) of the reinforcing bar including ribs
Fig. 1 — Labor and scheduling chart for horizontal welding of reinforcement bar protrusions of diameters 20 mm, 25 mm, and 28 mm.
Fig. 8 — Labor and scheduling chart for horizontal welding of reinforcement bar protrusions of diameters 20 mm, 25 mm, and 28 mm.
1Process Name: Column detailing the specific tasks required for welding rebar protrusions.
2Preparation of reinforcement protrusions for welding: Task for 20 mm diameter rebar, measured per joint.
3Welding of reinforcement protrusions: Task for 20 mm diameter rebar, measured per joint.
4Finishing work after welding: Task for 20 mm diameter rebar, measured per joint.
5Section heading: Horizontal single-pass welding of protrusions for 25 mm diameter.
6Preparation of reinforcement protrusions for welding: Task for 25 mm diameter rebar, measured per joint.
7Welding of reinforcement protrusions: Task for 25 mm diameter rebar, measured per joint.
8Finishing work after welding: Task for 25 mm diameter rebar, measured per joint.
9Preparation of reinforcement protrusions for welding: Task for 28 mm diameter rebar, measured per joint.
10Welding of reinforcement protrusions: Task for 28 mm diameter rebar, measured per joint.
11Finishing work after welding: Task for 28 mm diameter rebar, measured per joint.
1.1Unit of measurement: Column specifying the unit for each task (e.g., 'joint').
1.2Volume of work: Column specifying the quantity of work per unit (e.g., '1 node (3 joints)').
1.3Labor input, man-hours: Column detailing the estimated labor time required for the task.
1.4Accepted crew composition: Column listing the required workers and their skill grades (e.g., Gas cutter 3rd grade, Reinforcement worker 2nd grade).
1.5Process duration, hours: Column showing the calculated time to complete the specific process.
1.6Working hours: Timeline section showing the schedule of tasks plotted against time increments (0.2, 0.4, 0.6, etc., up to 2.8 hours).
2.1Unit of measurement for preparation (20mm): 'joint'.
3.1Unit of measurement for welding (20mm): 'Same' (joint).
4.2Unit of measurement for finishing (20mm): 'Same' (joint).
5.1Unit of measurement for preparation (25mm): 'joint'.
7.2Unit of measurement for welding (25mm): 'Same' (joint).
8.3Unit of measurement for finishing (25mm): 'Same' (joint).
9.1Unit of measurement for preparation (28mm): 'joint'.
10.11Unit of measurement for finishing (28mm): 'Same' (joint).
8.1Volume of work for finishing (25mm): 'Same' (1 node (3 joints)).
9.2Volume of work for finishing (28mm): 'Same' (1 node (3 joints)).
Fig. 1 — Labor and Time Schedule for Preparation, Welding, and Post-Welding Operations of Reinforcement Bar Extensions (Diameters 32, 36, and 40 mm)
Fig. 9 — Labor and Time Schedule for Preparation, Welding, and Post-Welding Operations of Reinforcement Bar Extensions (Diameters 32, 36, and 40 mm)
1Preparation of reinforcement extensions for welding (Diameter 32 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.432 man-hours, Personnel: Gas cutter (3rd category), Reinforcement worker (2nd category), Duration: 0.432 hours.
2Welding of reinforcement extensions (Diameter 32 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.498 man-hours, Personnel: Electric welder on automatic and semi-automatic machines (5th category), Duration: 0.498 hours.
3Final operations after welding (Diameter 32 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.429 man-hours, Personnel: Gas cutter (3rd category), Reinforcement worker (2nd category), Duration: 0.429 hours.
4Preparation of reinforcement extensions for welding (Diameter 36 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.453 man-hours, Personnel: Gas cutter (3rd category), Reinforcement worker (2nd category), Duration: 0.453 hours.
5Welding of reinforcement extensions (Diameter 36 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.522 man-hours, Personnel: Electric welder on automatic and semi-automatic machines (5th category), Duration: 0.522 hours.
6Final operations after welding (Diameter 36 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.453 man-hours, Personnel: Gas cutter (3rd category), Reinforcement worker (2nd category), Duration: 0.453 hours.
7Preparation of reinforcement extensions for welding (Diameter 40 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.471 man-hours, Personnel: Gas cutter (3rd category), Reinforcement worker (2nd category), Duration: 0.471 hours.
8Welding of reinforcement extensions (Diameter 40 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.546 man-hours, Personnel: Electric welder on automatic and semi-automatic machines (5th category), Duration: 0.546 hours.
9Final operations after welding (Diameter 40 mm) — Unit: 1 joint, Volume: 1 node (3 joints), Labor: 0.471 man-hours, Personnel: Gas cutter (3rd category), Reinforcement worker (2nd category), Duration: 0.471 hours.
Fig. 1 — Work Schedule and Labor Requirements for Welding Horizontal Rebar Outlets
Fig. 10 — Work Schedule and Labor Requirements for Welding Horizontal Rebar Outlets
1Task group for horizontal rebar outlets of 25 mm diameter, detailing preparation, welding, and finalization phases.
2Task group for horizontal rebar outlets of 20 mm diameter, detailing preparation, welding, and finalization phases.
3Task group for horizontal rebar outlets of 32 mm diameter, detailing preparation, welding, and finalization phases.
Fig. 1 — Work schedule and labor input chart for reinforcement bar welding processes.
Fig. 11 — Work schedule and labor input chart for reinforcement bar welding processes.
1Process Name — General description of the tasks being performed.
2Unit of Measurement — Specifies the unit by which the work volume is quantified.
3Volume of Work — The total amount of work to be completed for the specific task.
4Labor Input, person-hours — The estimated amount of labor required, measured in person-hours.
5Crew Composition — Details the roles and skill levels of the workers required for the task.
6Duration, hours — The estimated time required to complete the task.
7Working Hours (0.2) — Timeline scale marker.
8Working Hours (0.4) — Timeline scale marker.
9Working Hours (0.6) — Timeline scale marker.
10Working Hours (0.8) — Timeline scale marker.
11Working Hours (1.0) — Timeline scale marker.
12Working Hours (1.2) — Timeline scale marker.
13Working Hours (1.4) — Timeline scale marker.
14Working Hours (1.6) — Timeline scale marker.
15Working Hours (1.8) — Timeline scale marker.
16Working Hours (2.0) — Timeline scale marker.
17Working Hours (2.2) — Timeline scale marker.
18Working Hours (2.4) — Timeline scale marker.
19Working Hours (2.6) — Timeline scale marker.
20Working Hours (2.8) — Timeline scale marker.
21Gantt Chart Bar — Visual representation of the task duration and timeline.
22Gantt Chart Bar — Visual representation of the task duration and timeline.
23Gantt Chart Bar — Visual representation of the task duration and timeline.
Fig. 1 — Schedule of labor expenditure and process duration for welding reinforcement bar extensions (diameters 22mm, 25mm, and 28mm)
Fig. 12 — Schedule of labor expenditure and process duration for welding reinforcement bar extensions (diameters 22mm, 25mm, and 28mm)
1Process description: 'Preparation of reinforcement extensions for welding' - initial step for 22mm diameter bars.
2Process description: 'Welding of reinforcement extensions' - core welding task for 22mm diameter bars.
3Process description: 'Final works after welding' - post-weld finishing for 22mm diameter bars.
4Process description: 'Preparation of reinforcement extensions for welding' - initial step for 25mm diameter bars.
5Process description: 'Welding of reinforcement extensions' - core welding task for 25mm diameter bars.
6Process description: 'Final works after welding' - post-weld finishing for 25mm diameter bars.
7Process description: 'Preparation of reinforcement extensions for welding' - initial step for 28mm diameter bars.
8Process description: 'Welding of reinforcement extensions' - core welding task for 28mm diameter bars.
9Process description: 'Final works after welding' - post-weld finishing for 28mm diameter bars.
Fig. 1 — Schedule and resource allocation chart for welding reinforcing bar extensions of varying diameters
Fig. 13 — Schedule and resource allocation chart for welding reinforcing bar extensions of varying diameters
1Process for preparation of reinforcing bar extensions for welding, including cutting and cleaning
2Process for the actual welding of the reinforcing bar extensions using semi-automatic or automatic machines
3Final concluding works after welding, which may involve inspection and cleaning
4Preparation works specific to 36 mm diameter reinforcing bars prior to welding
5Welding works for 36 mm diameter reinforcing bars, utilizing specialized welding equipment
6Concluding post-weld works for 36 mm diameter reinforcing bars
7Preparation works for 40 mm diameter reinforcing bars, readying them for the welding process
8Welding of 40 mm diameter reinforcing bars, typically requiring higher power or longer duration
9Final works after welding 40 mm diameter reinforcing bars, ensuring joint integrity
10Timeline indicating process durations in hours, starting from 0.2 up to 2.8 hours
11Timeline intervals, specifically marking 0.4 and 0.6 hours
12Timeline intervals marking 0.8 and 1.0 hours
13Timeline intervals marking 1.2 and 1.4 hours
14Timeline intervals marking 1.6 and 1.8 hours
15Timeline intervals marking 2.0 and 2.2 hours
16Timeline intervals marking 2.4 and 2.6 hours
Fig. 1 — Cross-sectional and plan views of a metallic T-junction distribution block showing internal bores and intersection geometry.
Fig. 14 — Cross-sectional and plan views of a metallic T-junction distribution block showing internal bores and intersection geometry.
1Main metallic body/housing, rectangular block, serves as the structural casing for the internal flow channels.
2Internal vertical bore, upper section with a semi-spherical bottom profile, designed for specific fluid flow dynamics or fitting connection.
3Horizontal through-hole or channel, intersects with the vertical bore to distribute or combine flow.
4Lower vertical bore section, smaller diameter than the upper bore, continuing the vertical channel.
5Internal seating surface or shoulder at the transition of the vertical bore, potentially for sealing or component resting.
6Lower metallic base section of the main housing block.
7Chamfered entry edge at 45 degrees on the top surface, facilitating easier insertion of connecting pipes or fittings.
8Intersection edge where the vertical and horizontal bores meet, critical for flow transition and pressure management.
Fig. 1 — Cross-sectional detail of a grooved structural element with chamfered edge
Fig. 15 — Cross-sectional detail of a grooved structural element with chamfered edge
1Internal radius of the semi-circular groove, denoted as 'r' in the original specification, defining the inner boundary of the channel.
2External radius of the semi-circular groove, denoted as 'r+2' in the original specification, indicating a consistent offset or thickness of 2 units from the inner radius.
Fig. 1 — Cross-sectional profile of a keyway broach detailing key dimensions and cutting edge geometry
Fig. 16 — Cross-sectional profile of a keyway broach detailing key dimensions and cutting edge geometry
1Chamfered edge, providing a lead-in for the cutting tool or easing insertion into the workpiece
2Angled side wall of the cutting profile, contributing to the tool's cutting clearance and forming the '1.25b' upper width dimension
3Main central cutting channel or keyway profile, defined by its width 'b' and specific depth parameters 'D' and 'D+2'
4Overall width dimension reference point, aligning with the outer vertical edge of the tool body, marked as 'B'
Fig. 1 — Cross-section of a standard metal mold with a central U-shaped cavity for casting specimens
Fig. 17 — Cross-section of a standard metal mold with a central U-shaped cavity for casting specimens
4Top surface chamfer or bevel, indicating the angled edge at the opening of the mold cavity to facilitate demolding and prevent edge chipping
5Solid mold body, typically constructed from machined steel or cast iron, shown with diagonal hatching to represent solid metal cross-section
6Overall upper width of the mold block, corresponding to dimension 'l' in the original diagram
7Half-width dimension of the upper mold block, corresponding to 'l/2', indicating the distance from the edge to the central axis
8Horizontal dimension of the top edge chamfer, typically 5mm as indicated in the original diagram
9Vertical depth dimension of the top edge chamfer, typically 5mm as indicated in the original diagram
10Radius of the bottom curve of the U-shaped cavity, denoted as 'D1' in the original diagram, defining the semi-circular profile
11Half-width dimension of the lower mold block base, corresponding to 'A/2', measured from the edge to the vertical centerline
12Overall bottom width of the mold block base, corresponding to dimension 'A' in the original diagram
Fig. 1 — Elevation and plan views of a split mechanical clamp block with detailed internal bore dimensions
Fig. 18 — Elevation and plan views of a split mechanical clamp block with detailed internal bore dimensions
1Main body of the mechanical clamp block, shown in elevation view, illustrating the overall height and external profile.
2Internal fillet radius within the bore, providing a smooth transition to reduce stress concentration, indicated by dimension 'R'.
5Overall width of the clamp block body, denoted by dimension 'A' in the original diagram.
6Width of the upper conical opening or countersink, specified by dimension 'K'.
7Diameter of the upper cylindrical section of the bore, marked as 'd+3' in the original diagram.
8Depth of the upper cylindrical section of the bore before the conical transition, labeled 'h'.
9Overall height of the clamp block, indicated by dimension 'H'.
10Fillet radius at the bottom of the main bore, ensuring structural integrity at the step transition.
11Diameter of the lower, narrower cylindrical section of the bore, labeled 'd' in the original diagram.
12Section line A-A, indicating the cutting plane for the elevation view shown above.
13Chamfered corner on the exterior of the block, reducing sharp edges and possibly for clearance.
14Hatched area indicating the solid material of the block in the section view A-A.
15Split line or gap between the two halves of the clamp block, allowing it to tighten around a shaft or fitting.
16Another chamfered corner, symmetrical to element 13, defining the external geometry.
17Width of the flat section adjacent to the chamfer, indicated by dimension 'b'.
18Internal diameter of the main cylindrical bore in the plan view.
19Width of the central split or gap, denoted as '0.5' in the original diagram.
20Distance from the centerline to the outer edge of the block, half of the total depth, labeled 'b'.
21Horizontal dimension of the chamfered section, marked as 'a' in the original diagram.
22Distance from the edge of the block to the centerline of the bore, labeled 'b'.
23Distance from the centerline of the bore to the start of the split gap, labeled 'K'.
24Length of the split gap from the bore to the outer edge.
Tips & Recommendations
!
It is strictly prohibited to strike the welding arc by touching the wire to the elements of the copper or graphite reusable mold. This leads to weld contamination with impurities and localized destruction of the molding tooling.
!
Cutting reinforcing bar extensions with an electric arc is prohibited. The use of electric arc cutting alters the metal structure and leads to the formation of brittle quenching structures at the rebar ends. Use only oxy-fuel or plasma cutting.
i
To prevent the formation of a deep shrinkage cavity (crater) at the end of the welding process, make 2-3 short pauses of 3-4 seconds, positioning the wire perpendicularly and moving it from the center to the edges of the weld pool.
i
When working in low-temperature conditions, it is mandatory to cover the finished joint with a heat-resistant (asbestos or silica) cloth immediately after removing the mold. Rapid cooling of the weld in freezing temperatures provokes the appearance of cold cracks.
i
Do not subject flux-cored wire to repeated heat treatment (baking). This destroys the gas-forming and slag-forming components of the core, which will lead to massive weld porosity.