Extruded Graphite Heat Exchange Tube

I. Product Functions

Extruded Graphite tube is the core heat exchange element of graphite shell and tube heat exchangers. It is extruded from 0.8mm grade artificial graphite powder as the base material, combined with phenolic resin bonding and curing. It is an impermeable anti-corrosion graphite pipe. It is mainly used for heating, cooling, condensation, evaporation, heat recovery, hydrochloric acid absorption, and other processes under strongly corrosive chemical conditions. It is widely suitable for fine chemicals, waste acid recovery, pharmaceutical and pesticide, hydrometallurgy, pickling processes, and other strong acid corrosive scenarios.

Compared with molded graphite tubes, the extruded structure has uniform wall thickness, better toughness, smooth flow, and stronger resistance to medium scouring. According to different temperature conditions, it is divided into three standard grades: 150°C conventional heat treatment, 300°C high-temperature heat treatment, and 300°C carbon fiber reinforced high-temperature heat treatment. They are graded to suit low-temperature, medium-high temperature, and high-load continuous production conditions, effectively solving the industry pain points of metal pipes corroding and rusting, plastic pipes not being temperature resistant, easy aging, and low heat exchange efficiency.

II. Structural Forms

It adopts an integrated extrusion molding process. The tube body has uniform wall thickness, smooth inner and outer walls without pores or loose interlayers, high straightness, and precise concentricity, suitable for precision assembly of shell and tube heat exchanger tube sheets. The whole series uses 0.8mm particle size artificial graphite powder combined with phenolic resin. The base material particles are uniform and the density is stable.

According to heat treatment process and reinforced structure, it is divided into three product series with clear structural and performance grades:

1. 150°C conventional heat treatment extruded tube: Basic curing heat treatment process, fully cured resin, stable sealing performance. Suitable for conventional room temperature and medium-low temperature stable corrosive conditions, with high cost performance, suitable for long-term stable operation production lines.

2. 300°C high-temperature heat treatment extruded tube: High-temperature deep heat treatment process, effectively removing residual volatiles inside the tube, further improving resin crosslinking degree. The temperature resistance, thermal stability, and penetration resistance of the tube are greatly improved, suitable for medium-high temperature and frequent temperature fluctuation conditions.

3. 300°C carbon fiber reinforced high-temperature heat treatment tube: Based on the 0.8mm artificial graphite + phenolic resin system, a carbon fiber skeleton reinforcement structure is added, combined with 300°C high-temperature shaping heat treatment. The tube’s bending resistance, impact resistance, thermal shock resistance, and deformation resistance are significantly enhanced. It is specially designed for harsh conditions of high temperature, high pressure, strong scouring, and frequent hot-cold alternation.

The tube supports full-specification non-standard customization: standard diameters such as 55mm, 32mm, 25mm, and 19mm can be produced. Tube length and wall thickness can be customized on demand, adapting to replacement and new machine matching of various new and old shell and tube graphite heat exchangers.

III. Product Features

1. Fixed high-end base material formula, stable and controllable performance: The whole process uses 0.8mm grade artificial graphite powder as aggregate, with uniform particle size and high packing density, combined with pure phenolic resin curing. The base material has no impurities, low porosity, uniformly stable anti-permeation and anti-corrosion performance, and strong batch consistency.

2. Excellent extruded toughness, scouring resistant and not easy to crack: The extrusion process makes graphite particles and fibers oriented. The overall toughness of the tube is better than molded tubes. The tube wall structure is uniform, medium flow resistance is low, and material accumulation and scaling are not easy. It is suitable for large-flow, high-velocity corrosive medium heat exchange conditions.

3. Three-level heat treatment grading, precise working condition matching: The 150°C conventional grade is economical and durable, meeting most low-temperature acidic conditions; the 300°C high-temperature grade has strong thermal stability, temperature resistance, and penetration resistance; the 300°C carbon fiber reinforced grade has high strength and thermal shock resistance, capable of handling extreme hot-cold shock and high-pressure scouring. Clear selection, avoiding performance excess or insufficiency.

4. Uniform phenolic resin distribution, reliable anti-corrosion and anti-permeation: High-quality phenolic resin is uniformly mixed with graphite powder, extruded, and cured. The resin evenly fills the gaps between graphite particles, forming a dense structure that effectively prevents penetration and leakage of hydrochloric acid, dilute sulfuric acid, organic acids, and corrosive salt solutions. Stable corrosion resistance, suitable for various non-oxidizing strong acid conditions.

5. High heat exchange efficiency, no decay in long-term operation: Artificial graphite base material has excellent thermal conductivity, uniform and thin tube wall, low thermal resistance, and high heat exchange coefficient. The tube has no local looseness or interlayers, and heat exchange remains stable during long-term operation, without local overheating or heat exchange decay.

6. High precision, easy assembly, low operation and maintenance cost: Extrusion molding has high dimensional accuracy and flat tube openings, suitable for precision bonding to tube sheets and O-ring seal replacement. The tube is not easy to scale, easy to clean, and single tubes can be replaced individually, with low maintenance cost.

7. Full set of quality inspection documents deliverable: Can provide raw material particle size test reports, heat treatment process records, dimensional inspection reports, and hydrostatic test records, meeting equipment inspection, engineering audit, and archiving needs.

8. Professional protective packaging, high arrival integrity: Single-tube independent protection + frame reinforcement packaging prevents tube opening chipping and tube body collision cracks, ensuring the tube can be directly assembled on the machine upon arrival.

Product Limitations

1. Graphite material has inherent brittleness. Overpressure, severe impact, and strong bending are strictly prohibited. Forced alignment and stress during installation and connection are prohibited.

2. The phenolic resin system is not suitable for strong oxidants and high-temperature molten strong alkali conditions, which will accelerate resin aging and failure.

3. The 150°C conventional heat treatment version is not suitable for long-term high-temperature fluctuation conditions. Over-temperature easily causes resin softening and slight penetration.

4. The carbon fiber reinforced version has stronger mechanical properties, but it is still a brittle composite material and must avoid unilateral eccentric load and mechanical impact.

IV. Core Performance Indicators (Distinguished by Three Grades)

1. Unified base material parameters: Fixed use of 0.8mm grade artificial graphite powder, phenolic resin curing, uniform grains, dense structure, no loose pores, resistivity 8–15 μΩ·m, uniform and stable thermal conductivity.

2. 150°C conventional heat treatment type: Curing temperature 150°C, basic resin curing and forming, stable structure; suitable for conventional working temperature ≤160°C, conventional pressure ≤0.5MPa; suitable for stable, room temperature, medium-low temperature continuous acidic heat exchange conditions, with the highest cost performance.

3. 300°C high-temperature heat treatment type: High-temperature deep heat treatment shaping, removing internal residual solvents and small molecule substances, higher resin crosslinking degree; upgraded temperature resistance, thermal shock resistance, and penetration resistance, suitable for working temperature ≤200°C, able to withstand frequent temperature fluctuation conditions.

4. 300°C carbon fiber reinforced heat treatment type: Carbon fiber skeleton composite reinforcement + 300°C high-temperature shaping; bending strength, impact resistance, and thermal cracking resistance are greatly improved, pressure resistance is stronger, suitable for high-temperature, large-flow strong scouring, and frequent hot-cold alternation high-load harsh conditions.

V. Customization Service Model

1. Specification custom production: According to heat exchanger model, on-site working conditions, and temperature and pressure requirements, precisely match the three process versions: 150°C / 300°C / 300°C carbon fiber reinforced. Customize tube diameter, tube length, and wall thickness on demand.

2. Working condition adaptation and selection service: According to medium type, working temperature, pressure, medium flow rate, and scouring intensity, assist customers in precisely selecting the basic version, high-temperature version, or reinforced version, avoiding selection waste and equipment leakage failures.

3. Batch matching maintenance supply: Support batch customization of complete equipment matching tubes and old equipment replacement tubes, with long-term stable supply, suitable for factory annual maintenance spare parts reserves.

VI. Material Selection Standards and Precautions

1. Material selection standards: The whole series uniformly adopts 0.8mm artificial graphite powder + phenolic resin system, refusing to mix miscellaneous materials, fine powder, or loose extruded material; uniform particles and dense packing ensure tube strength and anti-permeation performance from the source. It is prohibited to use recycled graphite powder with uneven particle size and high impurities.

2. Precise selection of three grades for working conditions

   • Conventional stable low-temperature conditions, budget-friendly: choose 150°C conventional heat treatment extruded tube;

   • Medium-high temperature, large temperature fluctuation, penetration-sensitive conditions: choose 300°C high-temperature heat treatment extruded tube;

   • High temperature and high pressure, strong scouring, frequent start-stop, easy cracking and leakage conditions: must choose 300°C carbon fiber reinforced heat treatment tube.

3. Resin curing process requirements: Use uniform mixing of phenolic resin and graphite powder, extrusion molding, and staged curing process to ensure uniform resin distribution, consistent anti-permeation and anti-corrosion performance, and eliminate local penetration and poor local corrosion resistance.

4. Assembly and use requirements: Tube assembly should be evenly stressed. Forced alignment and eccentric compression are prohibited. Equipment startup should use gradient heating to avoid rapid cooling and heating. For high-temperature conditions, high-temperature heat treatment and reinforced versions should be preferred to extend equipment service life.

5. Machining process requirements: Integrated extrusion molding, uniform tube wall thickness, smooth inner and outer walls without burrs; precision cutting of tube openings, flat end faces, suitable for bonded sealing and O-ring sealing structures; precise temperature control during heat treatment to ensure uniform and stable performance of each batch of tubes.