To make the right choice of silicone tubing for your business, it is crucial to understand the pressure ratings of silicone tubing. Incorrect pressure calculations may lead to the failure or leakage of silicone tubing, causing significant losses to you.
This guide explains the working pressure, burst pressure and safety factor of silicone tubing, as well as the influencing factors and testing standards for you.
Working Pressure vs Burst Pressure vs Safety Factor of Silicone Tubing
Working Pressure
Working pressure refers to the maximum internal pressure that your silicone tubing can safely withstand during long-term continuous operation. It can also be called operating pressure or rated pressure.
Working pressure is typically derived from burst pressure after applying an appropriate safety factor and considering derating factors such as temperature, cyclic loading, media compatibility, and service life.
Burst Pressure
Burst pressure refers to the critical pressure value at which your silicone tubing ruptures or leaks during the pressure test. It is a theoretical limit value and cannot be used in actual operational conditions.
This figure needs to be tested through the prescribed standard method. It is mainly used to calculate the working pressure and to verify whether the safety factor meets the requirements.
Safety Factor
The safety factor, also known as the design factor or safety margin, is a crucial core parameter in engineering applications.
The safety factor cannot be chosen arbitrarily. It must be based on actual bursting test data rather than relying solely on theoretical calculations. After the tests are completed, you can calculate it using the formula: Safety Factor = Burst Pressure / Working Pressure.
You can refer to the industry standards in the table to understand the safety factor required in your production process or for your customers when purchasing silicone tubing.
| Application Field | Typical Safety Factor | Remarks |
| Medical / Biopharmaceutical | 3:1 to 5:1 | Higher safety requirements |
| Food and Beverage | 3:1 | Industry practice |
| Industrial Gases | 4:1 | For compressed gases |
| High-pressure Fluid (>1MPa) | 4:1 | Standard industrial practice |
4 Key Factors Affecting the Pressure Rating of Silicone Tubing
Wall Thickness-to-Inner Diameter Ratio
The ratio of wall thickness to inner diameter directly determines the pressure rating of the silicone tubing. When selecting the type, you should pay particular attention to this ratio. The larger the ratio, the higher the pressure rating. At the same time, you also need to consider cost and usage requirements to make a reasonable control.
The table below matches the impact of changes in wall thickness and inner diameter on the pressure rating of the silicone tubing and other effects caused. You can refer to it:
| Parameter | Effect on Pressure | Other Impacts |
| Increased wall thickness | Higher pressure rating | Reduced flexibility, larger bending radius |
| Larger inner diameter (constant wall thickness) | Lower pressure rating | Higher flow rate |
| Higher wall-thickness-to-inner-diameter ratio | Higher pressure rating | Increased material cost |
Hardness
The hardness of silicone tubing is usually indicated by Shore A. The hardness of silicone tubing has a significant impact on the pressure rating: the higher the hardness, the stronger the tensile modulus, and the better the pressure-bearing ability. The tensile modulus refers to the ability of your silicone tubing to resist deformation when it is stretched.
The high-hardness silicone tubing such as 80 Shore A is suitable for high-pressure applications, while the low-hardness tubing like 50 Shore A has better flexibility, but the pressure rating will be correspondingly lower.
Silicone tubes of different hardness are suitable for various applications. You can refer to the following table to select the silicone tube that suits your business needs:
| Shore A Hardness | Typical Applications | Characteristics |
| 50 | Peristaltic pumps, low-pressure transfer | High flexibility, good clamp compatibility |
| 60 – 65 | General industrial use | Balanced performance |
| 70 – 80 | High-pressure applications | Highest pressure rating, low elongation |
Reinforcement Layer
Reinforcement layer refers to adding a woven mesh or steel wire inside the silicone tube wall, which helps enhance the strength of your silicone tubing. In actual OEM production, braided reinforcement often causes OD tolerance variation. This may affect clamp sealing performance in sanitary fittings.
The pressure rating of non-reinforced and reinforced silicone tubing varies greatly. The pressure rating of the reinforced version is usually several times higher and is more suitable for high-pressure fluid transportation applications.
We have compiled different types of non-reinforced and reinforced silicone hoses and listed their corresponding applications. You can refer to the table below:
| Type | Working Pressure Range (psi) | Typical Applications |
| Non-reinforced standard tubing | 15 – 60 | Peristaltic pumps, low-pressure transfer |
| Non-reinforced high-pressure tubing (high hardness) | 25 – 60 | Higher-pressure service requiring transparency |
| Braided-reinforced tubing | 75 – 230+ | Industrial pressure transfer |
| Helical steel wire-reinforced tubing | 50 – 160 | Dual vacuum and pressure requirements |
Temperature
The working pressure of the silicone tubing will decrease as the temperature rises, although the derating rate varies depending on the silicone formulation and reinforcement structure.
Its normal continuous operating temperature range is from -60℃ to 200℃, while some formulations may tolerate short-term exposure up to 260°C. However, high-temperature aging will weaken the tensile strength, resulting in a decrease in the burst pressure.
The temperature-dependent pressure rating of silicone tubing varies depending on the formulation. When making purchases, you should ask the suppliers for the actual test data before making a decision.
Certifications and Pressure Test Standards for Silicone Tubing
Relevant Certifications
Silicone tubing is used in multiple industries, and each industry has its own entry requirements, especially in the food industry and the medical industry. The following table summarizes several relevant certifications, which you can refer to:
| Certification | Applicability | Explanation |
| FDA 21 CFR 177.2600 | Food and Beverage | Confirms material safety for repeated food contact |
| USP Class VI | Medical / Biopharmaceutical | Stringent biocompatibility standard for implantable/contact devices |
| ISO 10993 | Medical Devices | Biological evaluation of medical materials |
Test Methods
Mastering the testing methods related to silicone tubing pressure can help you verify the pressure-bearing performance of the silicone tubing and avoid risks associated with high-pressure usage. The following table summarizes the relevant industry certifications and international general standards:
| Test Type | Standard Method | Description |
| Burst Pressure Test | ASTM D1599 or equivalent hydrostatic burst test methods | Short-term hydraulic burst test |
| Tensile Strength | ASTM D412 / ISO 37 | Measures breaking strength |
| Hardness | ASTM D2240 / ISO 48 – 4 | Shore A scale |
| Elongation | ASTM D412 / ISO 37 | Elongation at break |
| Tear Strength | ASTM D624 | Die B or right-angle tear test |
| Vacuum Test | In-house method | Tests resistance to collapse under vacuum |
Test Protocol
You can also verify the pressure rating of the silicone tubing through the following standardized 5-step testing process. We recommend that each batch of your products undergo sampling tests and complete destructive tests.
- Proof Pressure Test: The silicone tube needs to maintain pressure for 30 – 60 seconds under working pressure. If there is no leakage or deformation, it can be verified that the silicone tube can safely withstand the rated pressure.
- Deformation Test: Maintain the pressure at the specified level for 1 minute and measure the size change. The outer diameter change should preferably be ≤ 5%.
- Burst Pressure Test: Apply pressure according to the test method of ASTM D1599 until the pipe material ruptures.
- Leakage Test: Maintain at 70% of the explosion pressure for 5 minutes. If the pressure drop does not exceed 2% and there is no obvious leakage, the leakage test is passed.
- Vacuum Collapse Test: After vacuuming for 1 minute, use the corresponding steel ball to detect the collapse situation.
FAQ
Will Sterilization Affect the Pressure Resistance of Silicone Tubing?
Yes. With prolonged use, repeated high-temperature sterilization will affect the mechanical properties of the silicone tubing, such as the tensile strength will decrease, the hardness will increase, and the silicone tubing will become brittle. These factors will lead to a decrease in the burst pressure of the silicone tubing.
Can Silicone Tubing Be Used for Transferring Oil-Based Hydraulic Fluids?
It is generally not recommended. Although silicone has excellent chemical resistance, it is incompatible with fuels such as gasoline and diesel. It will expand when exposed to hydraulic oil.
What Is the Minimum Bend Radius of Silicone Tubing under Pressure?
The higher the pressure, the more prone the bending part of the silicone tubing is to kinking. For different pressures, you can refer to the minimum bending radius: at low pressure (< 25% of the rating), it is 3–5 times the outer diameter; at medium pressure (25–50% of the rating), it is 5–8 times; at high pressure (> 50% of the rating), it is 8–10 times.
If you bend the silicone tubing too tightly, the wall of the tubing will become thinner locally, and the tubing is prone to cracking at the bending point.
How Does Fluid Viscosity Affect the Pressure Requirements of Silicone Tubing?
The viscosity of the fluid does not affect the pressure rating of the silicone tubing; it only increases the pressure drop during fluid transportation. If the viscosity of the fluid you need to transport is higher, the pump pressure required for transportation will be greater.
Therefore, when choosing the silicone tubing, you need to calculate the pressure drop based on your actual needs and leave a margin to ensure that the pressure of the equipment is lower than the rated working pressure of the tubing.
Can Cracked or Leaking Silicone Tubing under Pressure Be Repaired?
No. Adhesives, tapes, or patch fittings cannot restore the original pressure resistance performance of the silicone tubing, and will also cause stress concentration. Therefore, for silicone tubing used in pressurized environments, we recommend replacing the entire damaged section directly to avoid other risks.
Final Thoughts
Legensilico is a professional silicone manufacturer in China, capable of providing you with various silicone tubing. If you have any requirements for customizing or enhancing the pressure performance of the tubing, please feel free to contact us at any time. We can guarantee the high quality of the silicone tubing for you.
