When we discuss the role of nitrogen gas in cable manufacturing, particularly in cable curing, many questions arise. This blog aims to answer the most commonly asked questions and highlight how nitrogen plays a critical role in the cable industry.
What is Cable Curing?
Cable curing is the process of strengthening a cable’s insulation by cross-linking the polymer insulation material to form a durable 3D molecular network. This enhances the cable’s thermal and mechanical properties.
Types of Cable Curing Processes:
- Steam Curing: Uses steam as the curing medium.
- Dry Curing (Nitrogen Curing): Uses dry nitrogen gas.
- Peroxide Curing: Involves organic peroxides for cross-linking.
- UV Curing: Utilises ultraviolet light as the curing agent.
Among these, dry curing using nitrogen gas is the most widely adopted method due to its inertness and efficiency.
Why is Nitrogen Used for Cable Curing?
Nitrogen is preferred in cable curing for the following reasons:
- Prevents Oxidation: Its low oxygen content ensures that no oxidation occurs between the cable insulation polymer and the environment.
- Dry Medium: Being a dry gas, nitrogen prevents moisture-related defects like voids or weakening of the insulation.
- Enhances Safety: Nitrogen’s inert nature reduces the risk of explosions in heat-intensive curing processes.
- Economic: With nitrogen making up 78% of atmospheric air, it’s the most cost-effective gas for pressure or leak testing.
Can Other Gases Be Used for Cable Curing or Leak Testing?
Yes, other inert gases like argon and helium can technically be used. However, their cost makes them impractical:
Cost of production of Nitrogen ~ 100 times < Cost of production of Argon
Cost of production of Nitrogen ~ 1000 times < Cost of production of Helium
Due to nitrogen’s abundant availability and low production cost, it is the most feasible choice.
To get more clarity about the purity of nitrogen gas, please read our blog titled Understanding Nitrogen Purity in PSA Nitrogen Generators (1)
What Purity of Nitrogen is Required for Cable Curing?
Nitrogen purity for cable curing typically ranges from 99.9% to 99.99%, depending on the application requirements. These purity levels ensure minimal oxygen content desired for the application
To get more clarity about the purity of nitrogen gas, please read our blog titled Understanding Nitrogen Purity in PSA Nitrogen Generators (1)
How Much Nitrogen is Required?
The nitrogen requirement is not constant, it fluctuates depending on the machine and curing cycle. Certain phases demand a sudden flush of nitrogen. It’s best to consult the OEM of the cable manufacturing equipment for accurate specifications.
What is the Required Nitrogen Pressure?
Cable curing processes generally require nitrogen at a pressure of 12–18 Barg.
Sources of Nitrogen for Cable Curing
| Source | Cost (₹/Nm³) | Pressure (Barg) |
| Nitrogen Cylinders | ₹75-100 | Up to 200 |
| Liquid Nitrogen | ₹15-30 | Up to 20 |
| PSA Nitrogen Generator | ₹2.65 | Up to 250* |
*PSA nitrogen is generated at 7-8 Barg and boosted to required pressure using a nitrogen booster.
To read more about the cost of different sources of nitrogen, please read our blog, How to calculate the ROI (Return on Investment) of PSA Nitrogen Generator compared to Liquid Nitrogen or Nitrogen Cylinders (2)
Can High-Purity Nitrogen Be Used?
Yes, nitrogen with 99.99% or 99.999% purity can be used, but it significantly increases power consumption and cost.
The table below shows how electricity consumption affects the cost of production of nitrogen at different purity levels, assuming the cost of electricity as ₹8/- per unit, as per our blog titled Understanding Nitrogen Purity in PSA Nitrogen Generators (1).
Cost of Nitrogen by Purity Level
| Purity (%) | Power (kW/Nm³) | Cost (₹/Nm³) |
| 95.0000 | 0.22 | ₹1.76 |
| 99.0000 | 0.30 | ₹2.40 |
| 99.9000 | 0.33 | ₹2.64 |
| 99.9900 | 0.60 | ₹4.80 |
| 99.9950 | 0.80 | ₹6.40 |
| 99.9990 | 1.06 | ₹8.48 |
| 99.9995 | 1.32 | ₹10.56 |
As seen, nitrogen becomes significantly more expensive at higher purities due to the energy required for oxygen removal. Hence, 99.9% purity is optimal for cable curing.
Why PSA Nitrogen Generators Are the Preferred Choice
Modern cable manufacturing units prefer PSA nitrogen systems due to:
- Compact Design: Saves valuable floor space compared to bulky tanks.
- Fully Automatic Operation: PSA systems have auto-stop and idle features to conserve energy during low usage periods.
- In-House Generation: No reliance on vendors or delivery delays.
- Reduced Carbon Footprint: Eliminates transport emissions.
- Lower Operational Costs: PSA nitrogen is 5-10x cheaper than cylinders or liquid nitrogen.
Final Thoughts
Cable curing is a critical step in ensuring insulation strength and reliability in cables. Nitrogen gas, due to its dryness, inertness, and affordability, has become the industry standard. While traditional sources like cylinders or liquid nitrogen still exist, on-site PSA nitrogen generators offer unmatched cost efficiency, reliability, and sustainability.
Consult Us
For tailored solutions and expert consultation on nitrogen usage in cable curing, contact:
- Email: [email protected]
- Phone: 1800 3010 3394
- Website: www.absstem.com
References
- Absstem Technologies. (2024). Understanding Nitrogen Purity in PSA Nitrogen Generators
- Absstem Technologies. (2024). How to calculate the ROI (Return on Investment) of PSA Nitrogen Generator compared to Liquid Nitrogen or Nitrogen Cylinders
