A project manager or process engineer typically takes a substantial amount of time and effort to find the best solution to match the requirements of their application - one that will provide optimal performance while conforming to specifications and fitting the other constraints of the project (space, time, and budget). When so much consideration is taken on a large, expensive piece of equipment (as it should be), other ancillary equipment can be overlooked, or at least not given as much attention. But when you think about it, your process peripherals (piping, pumps, valves, columns, column internals, hoses, expansion joints, seals, gaskets, etc.) are critical extensions of your main process equipment; therefore it is equally important for the components of your system to be as durable and efficient as the main unit(s). When it comes to process piping, this is especially true – after all, you don’t want what goes through your pipe to go through your pipe.
Selecting a piping system for your project should be treated the same as buying any other piece of large equipment. Once the need for pipe is established in the system design, you need to identify what material of construction is required. If your process involves corrosive media then chances are you’ll be opting for some sort of lined pipe. The two main choices are fluoropolymer-lined pipe (the term used to refer to plastic materials like PTFE) and glass-lined pipe. The latter is created using a similar fabrication procedure as glass-lined vessels and other glass-lined equipment (read this post if you are interested in learning more about how glass lining is manufactured).
Based on the criteria we’ve outlined below, we’ll show you how glass-lined pipe and fittings are a viable solution for your process piping that offers safe containment of corrosive and hazardous media. And if you are already using glass-lined equipment it should make the decision that much easier for you (because shouldn’t you want your process pipe to be equivalent in quality and performance?).
Properties of Glass-Lined Piping
Glass-lined pipe features all the same properties and benefits found in glass-lined vessels and other glass-lined components. These properties include:
- Corrosion resistance – glass and is extremely resistant to corrosion by acids and alkalis (except for hydrofluoric acid and hot concentrated phosphoric acid)
- Anti-stick – many substances will not stick to glass but will stick to metal
- Purity – glass and has high quality standards for food and drug applications
- Flexibility – glass can handle a diverse range of chemical conditions.
- Ease of cleaning – glass-lined surfaces enable quick, easy cleaning and sterilization.
- Absence of catalytic effect – the composition of glass eliminates the possibility of catalytic effect that can occur in vessels made with various exotic metals.
Glass-Lined Pipe Performance
Many facilities have tested piping systems by installing various types in the same process conditions. While they have comparable performance in a lot of respects, there is often a greater deviation over an extended period of time. Here are the areas where glass-lined pipe surpasses other options when put to the test of time.
Unlike PTFE and other fluoropolymer lining materials that are soft and subject to abrasion and product build-up, glass is one of the hardest natural occurring materials. Glass lining maintains its smooth, impervious surface even in the harshest environments to greatly reduce or in some cases eliminate product build-up.
When it comes to the bond between the lining and the base, glass wins hands down. Since glass lining is fabricated using extremely high temperatures, a mechanical and chemical/molecular bond is created. This bond is permanent so the glass lining cannot separate from the base metal, making the design impervious to liner collapse from full vacuum conditions at high temperatures. With most other types of lining only a mechanical bond is created with the base metal. The lining materials can become brittle over time or even shrink which can cause separation from the base metal and make the liner subject to collapsing under vacuum.
A big concern that arises in any application that involves corrosive media is permeation, which needs to be carefully managed so as not to allow contamination of the lining or a chemical attack on the steel substrate. Glass lining is non-permeable and has no problem handling chemicals that can permeate fluoropolymer piping. Chances are if you are considering using glass-lined pipe then your process already involves a glass-lined reactor. If the material of construction is satisfactory enough for the large, most significant units in your process, you can be 100% sure that piping of the same fabrication will support your process requirements.
It’s no surprise that lined pipe is more expensive than unlined pipe, as there is a significant amount of extra work that goes into the manufacturing. Therefore, if your process can adequately function using a more basic piping system, then unlined pipe is the way to go; Glass-lined pipe is intended for processes that have more stringent requirements for corrosion resistance and cleanliness. When compared to the less expensive option of unlined pipe, though, the additional expense of glass lining is often compensated by the reduction in man hours required to clean lines (build-up can become a huge issue in metal pipes) so if you do have a product that accumulates in piping, glass lining is certainly a viable option.
Since lined pipe is constructed with some type of metal as the base, the arrangement of the piping system must be carefully measured since the material is rigid and offers no malleability. However, there is some level of versatility when it comes to PTFE-lined pipes in that the pipe lengths can be cut down to a desired size and reflanged to fit into the pipeline run. Glass-lined pipe sections do not offer this type of flexibility; since glass-lined equipment must be processed through a furnace their length cannot be altered. Therefore it is important to obtain accurate run dimensions prior to ordering your pipe. Spacers can be used to make up for differences in some instances but if a non-standard length is required then it must be manufactured to order.
Through assessing the performance of glass-lined pipe in real life situations it is found to be especially useful in the following applications:
- Sludge and scum piping systems
- Processes involving the transport of acidic or alkaline fluids
- Abrasive slurries
- High temperature fluids
If you’ve already assessed that glass-lined reactors are the right material of construction for your application then you know that glass-lined pipe will be a competent component. De Dietrich glass-lined pipe and fittings are made with the same care and workmanship as our larger glass-lined equipment. Piping is available in diameters up to 12”, with additional sizes available upon request, and is suitable for pressures up to 150 psig. DDPS stocks a variety of standard pipe lengths and elbows to enable quick delivery. For more information on glass-lined pipe and its chemical, mechanical and thermal properties download our Introductory Guide to Glass-Lined Equipment.