CST Twin-wall Steel Straight Pipes
ChangSha Talent (CST) concrete pumping straight pipes are renowned for its unique structure, prolonged lifespan and stable quality in China and worldwide.
Heat-treated for 6-80,000m³ service life
OEM pipe supplier for Zoomlion, XCMG, Schwing
Compatible with Sany, Putzmeister, CIFA
Patented design and production process
Balance of weight, wear-resistance and cost
Pipes are sold in China and also worldwide
Straight concrete pump pipes product specifications
| Parameter | High-Wear (Twin-Wall) Boom Pipe A | High-Wear (Twin-Wall) Boom Pipe B | High-Wear (Twin-Wall) Deck Pipe |
| Material | GCr15, Q345B, High-Cr cast iron | GCr15, Q345B, High-Cr cast iron | GCr15, Q345B, High-Cr cast iron |
| Wall Thickness | 2.7mm + 1.8mm (Inner/Outer) | 3.5mm + 1.8mm (Inner/Outer) | 4.2mm + 3.8mm (Inner/Outer) |
| Service Life | 60,000 m³ or more | 60,000 m³ or more | 80,000 m³ or more |
| Length | 1m, 2m, 3m (Customizable) | 1m, 2m, 3m (Customizable) | 1m, 2m, 3m (Customizable) |
| End Flange | SK / ZX / FM | SK / ZX / FM | SK / ZX / FM |
CST straight pump straight pipe innovative structure
- ① Outer Layer: Q355 seamless steel tube, hardened through cold drawing, reinforced with 6 ribs.
- ② Inner Layer middle segments: GCr15, HRC 63-65 integral quenching to ensure hardness evenness.
- ③ Inner Layer end segments: high wear-resistance High-Cr cast iron at both ends, HRC 62 above.
CST straight concrete pumping pipe is a Patented Innovation with US Patent No.: US 11,359,758 B2, please check out patent to have more information.
Technological innovations of CST straight pump pipelines
Structural innovation
▲ Special two-layer design, together with heterogeneously segmented inner lining, precisely reinforcing vulnerable pipeline areas.
▲ Strengthening of pipe end; segmented assembly of the concrete pump pipe body.
▲ Strengthening ribs is applied to the outer layer of the pump pipe
Material matching
▲ The inner lining material is divided into two types: end material and pipe body material. Depending on the different wearing condition, using High-Cr cast iron and bearing steel is used.
▲ The outer layer is made of Q355 seamless pipe, with high strength and strong pressure bearing capacity after heat treatment.
Process optimization
▲ Integral quenching is used, with good
penetrability and stable quality.
▲ For inner lining tube making, a unique technology is invented to weld the bearing steel.
▲ Adhesive bonding and filling are used to resist impact and solve the problem of knocking.
Technical characteristics of CST straight pipelines
Precise reinforcement of vulnerable areas
◎ By adjusting the structure, the wear-resistant material at the pipe end is changed to improve its wear resistance performance. At the same time, it can withstand high-temperature welding with flange without affecting its wear resistance;
◎ Strengthening area can be determined in according with the size and degree of actual wearing parts of the concrete pumping pipe.
Self-developed core processes
◎ Major technical breakthrough in welding and forming of bearing steel；
◎ Optimizing heat treatment for the inner and outer tubes, achieving high hardness for the inner tube and high strength and toughness for the outer tube；
◎ Composite assembly, using special adhesive bonding the joint and wear-resistant sleeve of the pipeline.
Real-time detection of key parameters
◎ The entire heat treatment process is automated with intelligent control, ensuring stable quality；
◎ The multi-stage structure enables full inspection of the inner tube hardness, cracks, roundness, etc；
◎ All finished product will be hydro-tested at a pressure of 17MPa, in accordance with industry standard, ensuring no leakage.
Why Changsha Talent’s straight concrete pump pipes are highly wear-resistant?
Key Words
- Uniqueness in structure design
- Segments of composite material
- Evenness in hardening
- Selection of more ware-resistant material
- Seamless Q355 steel tube
- High chromium cast iron
- GCr15 bearing steel
Changsha Talent (CST) has creatively re-designed the structure of inner tube of the twin-wall concrete pump straight pipes. It has several segments: several bearing steels tube in the middle and several high chromium cast iron rings at both ends.
A long inner tube, as long as 3m, can only be hardened through Induction Hardening, which might cause uneven hardening.
However, for CST straight inner tube segments, we process their hardening as a whole, because of their short length. Through-hardening ensures a even hardening of the whole inner tube, preventing possible weakness at certain points.
Segmentation design enable us to easily add wear-resistant high chromium cast iron rings at both ends of the inner tube.
The main body of the inner lining is made with GCr15 bearing steel, with hardness of HRC 62-65 after heat-treatment. In China, other producers usually choose 65Mn material, which is of less hardness and wear-resistance.
For the two ends, which are more vulnerable than the middle body, CST use much more wear-resistant high chromium cast iron, to strengthening inner tube’s durability.
Excellent quality material for inner lining and outer tube of straight pipe
1. Superior inner lining material quality
The inner tube is made of GCr15 bearing steel, which contains 0.95-1.05 carbon and 1.5-1.65 chromium. Its wear resistance is 50% higher than that of 65Mn steel, which is commonly used by other concrete pump pipe producer to make two-layer straight pipelines.
After through-hardening, carbides has been evenly distributed, realizing a hardness of HRC63-65, which results in above-standard strength and hardness.
GCr15 steel not only increase toughness, but also reduce weight of the straight pipeline
As show in the below tables, the Q value of the inner tube, made of GCr15 steel, is significantly higher than that made of 65Mn material. Take a 5.3mm-thick pipe for example, inner tube made with GCr15 has Q value of 1.6, while that made with 65Mn has Q value of only 1.0. The former is lighter by 60% than the latter one in weight. That’s why Changsha Talent choose GCr15 steel to realize weight reduction in concrete pump.
| Total thickness (mm) | Outer layer thickness (mm) | Inner layer thickness (mm) | Theory lifespan (10,000 m³) | Actual lifespan (10,000 m³) | Q Value |
| 4.5 | 1.8 | 2.7 | 9 | 6.5 | 1.44 |
| 5.3 | 1.8 | 3.5 | 12 | 8.5 | 1.6 |
| Total thickness (mm) | Outer layer thickness (mm) | Inner layer thickness (mm) | Theory lifespan (10,000 m³) | Actual lifespan (10,000 m³) | Q Value |
| 4.5 | 1.8 | 2.7 | 6 | 4 | 0.9 |
| 5.3 | 1.8 | 3.5 | 8 | 5.5 | 1.0 |
2. Tough and high-strength outer tube material for the straight pipe
The pipeline’s outer layer is made of high-quality Q355B structural steel. After being strengthened through cold drawing and heat treatment, the outer tube has increased its strength enough to withstand high pumping pressure, and support concrete transportation.
After undergoing a special processing, the elongation of the outer tube reaches 22.19%, the tensile strength reaches 773MPa, and the yield strength reaches714MPa. The residual stress of the outer tube is effectively eliminated, ensuring its high strength and toughness.
Q355B parameters before and after heat treatment, size: 1.8x12mm
| Condition | Before heat treatment | After heat treatment | Condition | Before heat treatment | Before heat treatment |
| Maximum force / Elongation/ Agt(%) | 12.18 | 22.19 | Maximum Deformation (Mm) | 7.714 | 14.214 |
| Maximum force (kN） | 15521.31 | 16689.4 | Tensile strength (Mpa) | 719 | 773 |
| Yield strength (kN) | 6922.5 | 15428.54 | Yield strength (kN) | 321 | 714 |
The strength of the metal material was tested by a material tensile test, and the tensile strength was found to be between 670-780 MPa. The minimum value was taken as the calculation the tensile strength value for the colddrawn and strengthened Q345B material: σb= 670 MPa.
Taking a safety factor of 1.5, the working pressure P工 of the outer tube was calculated using the following formula for pipeline pressure calculation:
P工 =( 2 * wall thickness * tensile strength σb) / inner diameter/ safety factor
= 2 * 1.8 * 670 / 130 / 1.5
= 12.37 MPa
The working pressure P工 of the straight pipeline at a safety factor of 1.5 is greater than the working pressure of a 63-meter pump truck. The ultimate breaking pressure Pj can be calculated as follows:
Pj=(2*wall thickness * tensile strength) / inner diameter
= 2 * 1.8 * 670 / 130
= 18.56 MPa
This value is greater than the current pipeline technology’s requirement of 17 Mpa.
The inner wall of the outer tube is machined with 6 reinforcing ribs for positioning, ensuring a <0.3mm ovality inner lining tube, after grouping. This will realize the coherence of the inner tube segments and the effective thickness of the wear-resistant layer.
Strict quality control & manufacturing process of straight pipe for concrete pump
| Key control point | Key control parameters | |
| 1 | Heat treatment of outer tube | Strength, toughness, elongation |
| 2 | Inner tube manufacturing | Welding, forming |
| 3 | Inner tube heat treatment | Hardness, micro-structure |
| 4 | Detection classification | Hardness, cracks, roundness |
| 5 | Assembly pressure test | pressure, welding, steps |
Quality control of raw materials for straight pump pipe
Professional personnel are appointed for quality check for 6 categories of raw materials, 38 testing indicators, clear testing tools, testing methods, testing frequency, and criticality. All raw materials are ensured to be checked and qualified before entering the production line.
