Magpie Hydrogenation Packing – Technical Requirements
1. Scope
This specification defines the technical requirements, testing methods, and inspection rules for flexible graphite packing rings (hereinafter referred to as “packing rings”) used in high-pressure hydrogenation valves, hydrogen-containing service valves, and H₂S-resistant valves. It also outlines the certification standards manufacturers must provide.
2. Normative References
The following standards are referenced in this document:
- GB/T 1801 – Product Geometric Technical Specifications (GPS) – Limits and Fits
- GB/T 1804 – General Tolerances – Tolerances for Linear Dimensions without Individual Tolerance Indications
- GB 2828 – Sampling Procedures for Inspection by Attributes – Part 1: AQL-Based Sampling
- GB 2829 – Sampling Procedures for Inspection by Attributes – Part 2: LQ-Based Sampling for Periodic Inspection
- JB/T 6623 – Determination of Sulfur Content in Flexible Graphite Sheet
- JB/T 6622 – Determination of Chlorine Content in Flexible Graphite Sheet
- JB/T 6370 – Test Methods for Physical and Mechanical Properties of Flexible Graphite Packing Rings
- ZB J22 010 – Tensile Strength Test Method for Flexible Graphite Sheet
- ZBJ 22013 – Ash Content Test Method for Flexible Graphite Sheet
- JB/T 6617 – Technical Conditions for Valve Flexible Graphite Packing Rings
3. Technical Requirements
3.1 Certification Requirements
Manufacturers shall provide valid test certification compliant with:
3.2 Materials
The properties of flexible graphite tape (sheet) used for packing rings shall meet the requirements in Table 1.
Table 1 — Flexible Graphite Material Performance Requirements
| Performance | Unit | Indicator |
|---|
| Tensile Strength | MPa | ≥ 3.5 |
| Ash Content | % | ≤ 5.0 |
| Sulfur Content | ppm | ≤ 200 |
| Chlorine Content | ppm | ≤ 50 |
| Fluorine Content | ppm | ≤ 100 |
The flexible graphite shall contain ≥ 98% pure carbon and shall not contain binders, lubricants, or other additives.
For metal-reinforced flexible graphite packing, INCONEL wire or other corrosion-resistant alloy wire shall be used. The packing shall:
- Have a service life ≥ 5 years
- Withstand long-term service in hydrogen, oil vapor, hydrocarbons + hydrogen + H₂S at 450°C
- Maintain stem sealing leakage within ISO 15848-2 Grade B limits.
3.3 Quality Requirements
3.3.1 Appearance
- No visible scratches, burrs, delamination, or other defects.
- Packing rings shall contain a corrosion inhibitor.
3.3.2 Structural Forms
Packing rings may be supplied in three forms (closed, single-open, double-open).
Open-type rings shall be cut at 45° (or 60° if specified) and must be smooth and free from unraveling.
(Refer to Figures 1, 2, and 3.)
3.4 Dimensions
The form and size may be defined by the user.
Dimensional tolerances for closed-type packing rings shall follow the requirements shown in Figure 1.
Unless otherwise specified, tolerances for other dimensions shall conform to GB/T 1804, Grade m (medium).
3.5 Performance Requirements
Packing ring performance indicators shall meet the requirements in Table 2.
Table 2 — Physical and Mechanical Properties of Packing Rings
| Performance | Unit | Indicator | Single Flexible Graphite | Metal Composite | Resin Composite |
|---|
| Density | g/cm³ | — | 1.4–1.7 (pre-formed) | ≥ 1.7 | ≥ 1.5 |
| Compression Rate | % | — | 10–25 | 7–20 | 10–25 |
| Recovery Rate | % | ≥ 35 | ≥ 35 | ≥ 35 | ≥ 35 |
| Temperature Loss¹ | 250°C | % | ≤ 0.3 | — | ≤ 1.0 |
| 450°C | % | ≤ 0.8 | ≤ 0.6 | — |
| 600°C | % | ≤ 8.0 | ≤ 6.0 | — |
| Friction Coefficient | — | ≤ 0.14 | ≤ 0.14 | ≤ 0.14 | ≤ 0.14 |
Note 1:
- When the metal’s melting point is lower than the test temperature, the test should not be conducted.
- For resin composite packing rings, the test temperature may be selected according to resin type and proportion.
4. Testing Methods
4.1 Visual Inspection
Packing ring appearance shall be examined visually.
4.2 Dimensional Measurement
- Use a vernier caliper (accuracy 0.02 mm, reading to 0.1 mm).
- Inner/outer diameters: mean of three evenly spaced measurements.
- Height: mean of three evenly spaced measurements.
4.3 Physical/Mechanical Properties
Test according to JB/T 6370.
4.4 Tensile Strength of Graphite Tape
Test according to ZB J22 010.
4.5 Ash Content
Test according to ZBJ 22013.
4.6 Sulfur Content
Test according to JB/T 6623 (≤ 50 ppm).
4.7 Chlorine Content
Test according to JB/T 6622.
5. Inspection Rules
5.1 Factory Release
All packing rings must pass quality inspection before shipment.
5.2 Inspection Categories
- Factory inspection
- Type inspection
5.3 Sampling
Random sampling from warehouse inventory.
5.4 Factory Inspection
5.4.1 Inspection Items
Items specified in Sections 3.2–3.3.
5.4.2 Batch Rules
- Same specification = one batch (per shift or order).
- Sampling per GB 2828:
- General inspection level: IL = II
- AQL = 10
- 100% visual inspection of appearance.
5.5 Type Inspection
5.5.1 Conduct Type Inspection When:
a. Product structure, material, or process changes significantly
b. Continuous production for 1 year
c. Production suspended > 6 months
d. Factory inspection results differ significantly from last type test
e. Required by quality supervision authorities
5.5.2 Type Inspection Items
Items in Sections 3.1–3.4.
5.5.3 Sampling Requirements
Follow GB 2829, one-time sampling plan, RQL = 30, judgment level = II.
6. Marking, Packaging, Transportation, and Storage
6.1 Marking
Each packing box shall include:
- Product name
- Manufacturer name
- Trademark
- Model or marking
- Gross/net weight
- Production date or batch number
6.2 Packaging
6.2.1 Protection
Packaging shall ensure no damage or loss during transportation or storage.
6.2.2 Packing List
Must include:
- Product name
- Trademark
- Manufacturer
- Quantity
- Specifications
- Manufacturing date
6.2.3 Qualification Certificate
Must include:
- Batch number
- Standard number
- Inspector name/code
6.3 Transportation & Storage
- Protect from rain and moisture during transportation.
- Store in a clean, dry warehouse.It's important to know about Google SEO to help your website rank higher in search results.