How Does Line Sizing Affect the Cost and Design of Hydrogen Systems?
Hydrogen line sizing plays an important role in achieving efficient, safe, and reliable fluid system performance. Because hydrogen is a small-molecule gas that is often stored and transported at high pressures, tubing size selection can directly influence flow characteristics, pressure drop, system responsiveness, and overall operating efficiency. In this video, you'll learn key considerations for sizing tubing and flow paths in hydrogen applications and how proper design decisions can help support system integrity. Understanding the relationship between pressure, flow requirements, and component selection can help engineers optimize hydrogen production, distribution, storage, and dispensing systems.
Video Transcript
CRAIG GIFFORD:
Welcome to Ask Swagelok. I'm Craig Gifford, here again with Chuck Hayes, who is Swagelok’s global technical lead for clean energy. And we've been discussing the design differences between hydrogen fluid systems and oil and gas fluid systems. So, today, Chuck, let's talk about line sizing a little bit. How does line sizing affect cost and design of hydrogen fluid systems?
CHUCK HAYES:
Sure. Let's talk real quick about line sizing and how we calculate line sizing as engineers. We do that by using calculators, online calculators and so forth, to be able to figure out both our line size to control velocity and pressure drop. The problem is that hydrogen is not an ideal gas. Ideal gases are things like nitrogen and a lot of the other gases we deal with. But hydrogen is not. So, hydrogen actually changes its density depending on how compressed it is and what the pressures are. So, what that leads to is that the calculators don't give you a good response, and it might overestimate pressure drop or overestimate velocities.
CHUCK HAYES:
What we find is that in order to get the right system, oftentimes what designers will do is they'll go back to their old world of oil and gas. And in oil and gas, if you want to reduce pressure drop or reduce velocity, you go up in size. So, as designers are looking at this that have experience in oil and gas, they keep oversizing systems.
CRAIG GIFFORD:
Because that's what they're used to.
CHUCK HAYES:
That's what they're used to doing. Right, exactly. So, what happens is—let's take a perfect example. We might have a system that, from history, we would know should be a half‑inch system. But, when you do the calculations, it might come up as three‑quarter; but you can be concerned about velocity. So, then you go up to a one‑inch. And the difference between going between three‑quarter and one‑inch is about eight times cost when you do all the components. It makes it much more difficult to get a final design.
CHUCK HAYES:
So, we at Swagelok have been training on this and learned, and what we've done is got all of our field engineers—and we've got a group of these throughout the world—to be able to help our customers understand this better and be able to design their systems to be most appropriate for hydrogen. We're able to help you with that in the future.
CRAIG GIFFORD:
Great. Well, thank you, Chuck. And thank you for joining us at Ask Swagelok.
