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Hollow Glass Microsphere
ITM11480, ITM11537, ITM11676, ITM11687, ITM11693, ITM11694

3M™ Glass Bubbles S38HS are hollow glass spheres with a typical density of 0.38 g/cc and an isostatic crush strength of 5,500 psi. These glass bubbles are designed for buoyancy and insulation in ultra-deep water applications in oil and gas drilling. The bubbles produce strong, stable voids and low thermal conductivity, helping coatings achieve the necessary compressive strength.


  • Glass bubbles in flexible flowlines are half the weight of conventional pipe-in-pipe construction
  • Reduces overall pipe diameter requiring fewer and smaller ships for transportation
  • Decreases weight and increases buoyancy for lower density in finished parts
  • Provides excellent water and oil resistance for use in underwater applications
  • Decreases thermal conductivity in syntactic foam compositions
  • Good strength-to-density ratio for use in a variety of oil and gas applications

What are 3M™ Glass Bubbles?

3M™ Glass Bubbles are engineered hollow glass microspheres made from water-resistant and chemically-stable soda-lime borosilicate glass. Like all 3M glass bubbles, our 3M™ Glass Bubbles S38HS are water and oil resistant, providing better utility in underwater applications. Additionally, they are non-combustible and non-porous, so they do not absorb resin; and their low alkalinity makes this product compatible with most resins while providing a stable viscosity and a long shelf-life.

These low-density particles are used for many demanding applications across a wide range of industries to provide temperature and pressure resistance, reduce part weight, lower costs and enhance overall product properties. For these reasons, 3M glass bubbles are a superior alternative to many conventional fillers and additives such as silica, calcium carbonate, talc and clay.

Strength-to-Weight Ratio

The benefits don’t end there; although 3M glass bubbles S38HS have thin walls, they have a good isostatic crush strength of 5,500 psi, meaning they can survive both the rigorous demands of processing and enormous water pressure at depth. In turn, their low thermal conductivity makes them ideal additives in insulation for pipelines and production risers – helping to ensure that hot oil continues to flow to the surface rather than cooling and slowing. S38HS bubbles have a fractional survival rate of 80% or more, at 5,500 psi for consistent performance and greater survivability.

Subsea Flowlines

What does this mean for the oil and gas industry? Conventional flowline construction, such as pipe-in-pipe, is proving to be impractical and too costly for use at today’s deeper depth oil and gas drilling (10,000 ft. /3,000 m. and more). Although pipe-in-pipe offers the best U-value (insulating value) and longest cool-down times, the added weight and bulk of its construction can make it more difficult and costly to lay – and too heavy to support in deeper waters, which is of particular concern when using drilling risers.

Importantly, there are some peripheral subsea hydrocarbon reservoirs that are economically viable at reach-out distances of 31 miles (50 km), or more. Longer subsea pipe lengths coupled with hotter drilling conditions require flowline insulation with increased mechanical strength and reduced heat transfer. 3M glass bubbles provide the solution to this drilling need. Using glass bubbles in syntactic foam insulation creates a pipeline that can stand up to demanding depth, pressure and temperature conditions.

Consider the benefits of alternatives, such as wet insulated pipe or flexible insulated flowlines. Both options consist of a single pipe coated with 3M glass bubble-filled syntactic foam insulation coatings, such as syntactic urethane. These pipes are less than half the weight of pipe-in-pipe, making them more practical for use at greater depths and in longer runs. Additionally, because this construction reduces overall pipeline diameter, more pipe can be wound per spool, requiring fewer and smaller ships – making installation faster, easier and more economical. Because of these, and many other factors, wet pipe insulation now accounts for the majority of all new deep water subsea flowlines.

Pushing the Limits: a Proud History of Innovation

Hollow glass bubble technology was developed by 3M in the 1960s. Riser buoyancy modules and wet pipe flowline insulation using the first glass bubble-filled syntactic foams were capable of surviving down to 5,000 feet below sea level. Today, advancements in the strength-density ratio of glass bubbles enables these materials to be used at any depth – all the way to the bottom of the ocean – more than 36,000 feet (10,972 meters).

Other Applications and Industries Include:

  • Paints and coatings
  • Buoyancy
  • Transportation
  • Syntactic urethane, silicone and polypropylene