Tube Welds vs Port Welds for Containment Bladders: a Comparative Guide

The difference between tube welds & port welds

Radio frequency welding produces two efficient means of allowing in-flow and evacuation of a particular medium (e.g. air, gas, fluid, etc.) into or out of a containment bladder. For medical devices, inflatables and other applications, tube and port welds come with different advantages in aiding the medium’s movement.

  • A tube weld is used when the medium will eventually have to evacuate the bladder. It allows the medium to flow freely.
  • A port weld allows you to switch the connection that the medium flows through. The in-flow or evacuation of the medium may be interrupted by a cap.

Below is a handy guide to the important differences in welding procedures, common applications and unique advantages of tubes and ports as conduits for media held in a containment product.

High frequency tube welding TPU

Differences in the welding process

Tube welds and port welds use a form of sealing known as radio frequency welding. Radio frequency welding uses a high frequency current to heat and seal together two sheets of compatible material. The process often uses two tooling dies (i.e. molds) that put pressure on the heated materials and form the seal.

Though they have similar functions, tube welds and port welds require slightly different RF welding methods:

Tube weld manufacturing

A tube weld utilizes an RF welding machine to seal a clear, thermoplastic polyurethane (TPU) tube(s) into the edge or seam of the containment bladder. The thickness of the tube and the bladder material must be compatible and determined before the welding process begins.

This type of weld requires tooling dies. A medical containment bag often requires a rounded mandrel that holds the tube in place as it is inserted between two sheets of material. The tooling dies then apply pressure to the heated material to create an airtight seal around the tube.


Port weld manufacturing

Unlike a tube weld, a port weld has more flexibility in its design, including size, placement and shape.

In order to make a port weld, a hole is punched into a flat sheet. A port flange is inserted into the bladder, large enough to allow the stem to protrude from the hole. A smaller electrode then welds the flange to the sheet.

Common applications for tube & port welds

Containment bladders are used in a variety of environments, from the medical industry to the auto industry. Therefore, tubes and ports are found in a variety of products, large and small.


A tube is used in applications where a medium must easily flow through the same channel.

Expect to find tube welds in the following products:

  • Medical IV bags
  • Blood bags
  • Feeding bags
  • Blood pressure cuffs
  • Water hydration bladders
  • Car seat lumbar support bladders


A port is used in products that require different tubes or hoses to be switched out of the bladder.

Expect to find port welds in the following products:

  • Flotation and inflatable devices
  • Air casts
  • Ostomy care bags
  • Inflatable pillows
  • Wine and baby food bladders
  • Spill containment bladders

Tamper-proof port seals

When a product is only for one-time use, it’s common to see a tamper-proof port. This type of port has a special seal or barrier over the aperture, typically thin and puncturable, that indicates whether or not the product has already been used.

Tamper-proof port seals are common to see in medical applications where safety protocol demands evidence of tampering to prevent error or contamination (e.g. drug vials and IV port seals).

Advantages of tubes vs ports

The differences between tubes and ports lend themselves to specific advantages. When would a tube be a better option than a port, and vice versa?


  • A tube’s permanent bond makes it less impervious to leaking—a major reason for its prevalence in the medical industry.
  • Numerous tubes can be welded into the perimeter of the bladder.
  • It’s a good option for bladders that are not portable or easily accessible.


  • Ports are often a cheaper option, and you can swap out the tube rather than changing the entire bladder.
  • Ports can make an item more portable.
  • A port is useful where a larger tube is required, and the size of the tube can be tapered after the fact.
  • Ports can be straight connectors, angled connectors or 90 degree connectors. This is useful when something else must be connected horizontally or perpendicularly.

Implementing a tube or port into your product

SealWerks provides radio frequency welding services, including tube welds and port welds for your product. To learn more about how you can incorporate a tube or port into your design, contact us.