Professional Introduction to Ramie Packing

Ramie packing is a braided sealing packing made primarily from natural ramie fibers. Valued for its excellent cost-performance ratio and environmentally friendly characteristics, it maintains a significant position in the field of traditional industrial sealing. As a fundamental solution for mechanical sealing, it is particularly suitable for equipment operating under medium-low pressure and medium-low speed conditions.

Core Material Characteristics

1. Natural Fiber Base Material:

   • Utilizes high-quality long ramie fibers (fiber count 8-10 Nm).

   • Natural hollow structure provides good elasticity and oil absorption.

   • Fiber strength reaches 300-500 N/cm (dry state).

2. Impregnation Treatment Process:

   • Basic Type: Pure natural fiber braid.

   • Oil-Impregnated Type: Impregnated with mineral oil (oil content 18-22%).

   • Graphite Type: Composite with graphite powder (content 15-20%).

3. Environmental Advantages:

   • 100% free of asbestos and toxic substances.

   • Biodegradation rate > 95% (OECD 301B).

   • Compliant with RoHS and REACH certifications.

Typical Performance Parameters

• Temperature Range: -20°C to 180°C (Graphite type can reach 200°C for short periods).

• Pressure Tolerance: ≤ 2.5 MPa (Graphite type performs best).

• Linear Speed: ≤ 8 m/s (in water medium).

• Friction Coefficient: 0.05 - 0.15 (varies depending on the impregnant).

• Compression Rebound Rate: ≥ 65% (after 20% compression).

Main Product Series

1. Economy General-Purpose Type:

   • Suitable for mild media such as clean water and low-pressure steam.

   • Typical service life: 3,000 - 4,000 hours.

   • Cost is only about one-third that of synthetic fiber packing.

2. Oil-Impregnated Enhanced Type:

   • Mineral oil impregnation improves lubricity.

   • Particularly suitable for saltwater-containing media, such as marine seawater pumps.

   • Extrusion resistance improved by 30%.

3. Graphite Composite Type:

   • Incorporates natural flake graphite.

   • Temperature resistance improved to 180°C.

   • Special model for steam valves.

Professional Application Guide

• Preferred Scenarios:

  • Agricultural irrigation pump shaft seals.

  • Ship ballast water systems.

  • Low-pressure steam valves.

  • Retrofitting of traditional industrial equipment.

• Limitations:

  • Not suitable for strong acid/alkali media (pH < 3 or > 11).

  • Avoid use in precision high-speed equipment (> 10 m/s).

  • Media containing solid particles require a flushing system.

Installation and Maintenance Key Points

1. Installation Specifications:

   • Shaft surface finish requirement: Ra 1.6 - 3.2 µm.

   • Use 45° angled cuts, installed with 90° stagger.

   • Tighten ring by ring to 20-25% compression.

2. Operation and Maintenance:

   • Initial run-in period: 2-4 hours (at 60% load).

   • Normal leakage control: 60-100 drops/minute.

   • Replenish lubricating grease every 3 months (except for oil-impregnated type).

3. Replacement Criteria:

   • Continuous leakage > 200 drops/minute.

   • Packing hardens and loses elasticity.

   • Axial wear exceeds 30%.

Technology Development Status

Modern ramie packing maintains its competitiveness through the following improvements:

• Fiber Modification: Enhances corrosion resistance.

• Environmentally Friendly Impregnants: Food-grade white oil replaces mineral oil.

• Composite Braiding Process: Blended with carbon fibers to increase strength.

With its "natural, economical, and reliable" characteristics, ramie packing remains a practical choice in the field of low-pressure sealing against the backdrop of increasingly stringent environmental requirements. It is particularly suitable for applications with limited budgets and mild operating conditions. With proper selection and installation, its service life can reach over one year.

Basic Physical Property Parameters

Performance Indicator	Standard Type	Oil-Impregnated Type	Graphite Type	Test Standard
Main Composition	Ramie Fiber	Ramie + Mineral Oil	Ramie + Graphite	-
Main Composition	1.10-1.20	1.15-1.25	1.25-1.35	ISO 1183
Fiber Count (Nm)	8-10	8-10	6-8	GB/T 5881
Operating Temp. (°C)	-20 ~ 120	-10 ~ 150	0 ~ 180	ASTM D865
Operating Pressure (MPa)	≤ 1.6	-10 ~ 150	≤ 2.5	≤ 2.5
Linear Speed (m/s)	≤ 8	-10 ~ 150	≤ 5	≤ 5

Mechanical Properties

Parameter	Standard Type	Oil-Impregnated Type	Graphite Type
Tensile Strength (N/cm)	300-400	0.12-0.15	400-500
Compression Rate (%)	15-18	18-20	20-22
Rebound Rate (%)	15-18	≥ 70	20-22
Friction Coefficient	0.12-0.15	0.08-0.10	0.05-0.08

Specification Parameters

Size (mm)	Cross-Section Tolerance	Cross-Section Tolerance	Braid Density (strands/cm)
3×	±0.15	10-25	12-14
5×5	±0.20	25-50	10-12
6×6	±0.25	25-50	8-10
8×8	±0.30	80-120	6-8

Medium Resistance Performance (Service Life in Hours)

Medium	Medium	Medium	Graphite Type
Clean Water	3,000-4,000	4,000-5,000	5,000-6,000
Seawater	2,000-3,000	2,500-3,500	3,000-4,000
10% NaOH	1,000-1,500	1,500-2,000	2,000-2,500
Machine Oil	800-1,200	2,500-3,500	2,500-3,000

Installation Parameters

Item	Standard Requirement	Specialized Tool
Specialized Tool	Ra 1.6-3.2 µm	Surface Roughness Tester
Cut Angle	45° ± 2°	Angle Cutter
Tightening Force	20-30 N/cm	Packing Compressor Tool
Run-in Time	2-4 hours	Speed Monitoring System