S22053 Stainless Steel Heat Exchanger Tube Purchase Technical Requirements

I. General Provisions

This technical requirement is applicable to the procurement of S22053 stainless steel heat exchange tubes required for [specific project name]. The purpose is to clearly define the technical parameters, quality requirements, inspection methods, and delivery aspects of these heat exchange tubes, ensuring that the purchased heat exchange tubes meet the usage requirements and relevant standards and specifications of the project.

II. Product Name and Model

Product Name: S22053 Stainless Steel Heat Exchange Tube

Model Specifications: Specific specifications are detailed in the purchase list, including but not limited to the outer diameter, wall thickness, length, heat exchange area, etc. of the heat exchange tube.

III. Execution Standards

The manufacturing, inspection, and acceptance of the heat exchange tubes should comply with the following standards. In case of any conflict, the latest version or higher requirements shall prevail:

Material Standards: GB/T 24593 "Boiler and Heat Exchanger Stainless Steel Seamless Pipes", ASTM A789/A789M "Commonly Used Ferritic - Austenitic (Dual Phase) Stainless Steel Seamless and Welded Pipes"

Manufacturing Standards: GB 151 "Heat Exchangers", ASME BPVC. VIII.1 "Pressure Vessel Construction Rules"

Inspection Standards: GB/T 222 "Permissible Deviations of Chemical Composition for Steel Products", GB/T 228.1 "Metal Materials - Tensile Test - Part 1: Room Temperature Test Method", GB/T 241 "Metal Pipes - Hydraulic Test Method", etc.

IV. Technical Parameter Requirements

(1) Material Properties

1. Chemical Composition: The chemical composition of S22053 stainless steel should comply with the following table:

| Element | C | Si | Mn | P | S | Cr | Ni | Mo | N | |---|---|---|---|---|---|---|---|---|---|

| Content (%) | ≤0.03 | ≤1.00 | ≤2.00 | ≤0.030 | ≤0.020 | 21.0 - 23.0 | 4.5 - 6.5 | 2.5 - 3.5 | 0.08 - 0.20 |

2. Mechanical properties: At room temperature, the mechanical properties of the heat exchange tubes should meet the following requirements:

| Item | Tensile strength (MPa) | Yield strength (MPa) | Post-rupture elongation (%) | Hardness (HB) | |---|---|---|---|---|

| Indicator | ≥620 | ≥450 | ≥25 | ≤290 |

(II) Geometric Dimensions

1. Outer diameter and wall thickness: The allowable deviation of the outer diameter is ±1%, and it shall not exceed ±0.5mm; the allowable deviation of the wall thickness is ±10%.

2. Length: The allowable deviation of the length is ±5mm. Special requirements should be noted in the purchase order. Straightness: The straightness per meter shall not exceed 1.5mm, and the straightness of the entire length shall not exceed 0.15% of the length of the heat exchange tube.

3. Roundness: When the outer diameter is not greater than 108mm, the roundness shall not exceed 80% of the allowable deviation of the outer diameter; when the outer diameter is greater than 108mm, the roundness shall not exceed 90% of the allowable deviation of the outer diameter.

(III) Surface Quality

1. The surface of the heat exchange tube should be smooth and clean, and there shall be no cracks, folds, scars, burrs, pits, oil stains, etc. that affect its use.

2. Minor scratches, dents, etc. shall have a depth not exceeding 5% of the wall thickness and not exceeding 0.5mm. Otherwise, they should be ground, and the ground area should have a smooth transition and the wall thickness shall not be less than the designed wall thickness.

V. Manufacturing Requirements

(1) Raw Materials

1. Raw materials should be selected from high-quality S22053 stainless steel ingots or tube blanks, with good metallurgical quality, and shall not have shrinkage cavities, inclusions, segregation, etc.

2. Quality certificates should be provided, indicating the furnace number, batch number, chemical composition, mechanical properties, heat treatment state, etc., and shall comply with relevant standard requirements.

(2) Manufacturing Process

1. The heat exchange tube is manufactured by seamless steel pipe, and the manufacturing process includes hot rolling, cold rolling (drawing), etc. The specific process should be determined by the manufacturer according to the actual situation, but the performance of the heat exchange tube shall meet the requirements.

2. For cold rolled (drawn) tubes, appropriate heat treatment, such as solution treatment, should be carried out during the manufacturing process to ensure the mechanical properties and corrosion resistance of the material.

3. The ends of the heat exchange tube should be flat, without burrs, and the cutting edge should be perpendicular to the axis, with an inclination angle not exceeding 1.5°.

(III) Marking

Each heat exchange tube should be marked at a prominent position with the following information: manufacturer's name or trademark, material code, specification model, furnace number or batch number, manufacturing date, etc. The marking should be clear and durable, and easy to identify and trace.

VI. Inspection and Acceptance

(1) Inspection Items

1. Chemical composition inspection: Each batch of heat exchange tubes should undergo chemical composition analysis, which can be carried out by using spectroscopic analysis or chemical analysis methods. The inspection results should comply with this technical requirement and relevant standard regulations.

2. Mechanical property inspection: At least 2 samples of each batch of heat exchange tubes should be taken for tensile tests, and the tensile strength, yield strength, and elongation after fracture should be inspected. The test results should meet the requirements.

3. Geometric Dimension Inspection: Use appropriate measuring tools, such as vernier calipers, micrometers, straight rulers, etc., to inspect the outer diameter, wall thickness, length, straightness, roundness, etc. of the heat exchange tube. The inspection quantity of each batch shall be no less than 5% and no less than 2 tubes.

4. Surface Quality Inspection: Conduct a comprehensive inspection of the surface of the heat exchange tube using visual inspection methods. Defects found shall be handled in accordance with this technical requirement.

5. Hydraulic Test: Each heat exchange tube should undergo a hydraulic test. The test pressure is 1.5 times the design pressure, and the holding time shall be no less than 5 seconds. There shall be no leakage. If an air pressure test is required, it shall be separately agreed upon in the contract.

6. Intergranular Corrosion Test: Take no less than 2 samples of each batch of heat exchange tubes for intergranular corrosion tests. The test method shall follow GB/T 4334 "Stainless Steel Intergranular Corrosion Test Method" or other appropriate methods. The test results shall have no intergranular corrosion tendency.

(II) Inspection Methods

1. Chemical composition analysis methods shall be carried out in accordance with GB/T 223 series standards or spectroscopic analysis methods. 2. The mechanical performance test methods shall be carried out in accordance with the GB/T 228.1 standard.

3. The geometric size inspection shall be conducted using general measuring tools and measured according to the specified methods in relevant standards.

4. The surface quality inspection shall be carried out by visual inspection, and tools such as magnifying glasses may be used if necessary.

5. The hydraulic test shall be carried out in accordance with the GB/T 241 standard, with clean water or other suitable liquids as the test medium.

6. The intergranular corrosion test shall be carried out in accordance with the GB/T 4334 standard.

Tags: Stainless steel heat exchange tubes