Disclaimer: No, this won't work on Wizard's Den servers. Sorry. They hate fun unpredictable game content over there, move to Goob, KS14, Funky or even Einstein Engines to perform this.

What is subframe?

Subframe is a family of coding oversights that relies on the game processing every single entity in some defined "update" order.
In SS14, it most commonly manifests as single pipelines (of any entity, not just real gas pipes) behaving inconsistently.
* For example, two logic gates wired to each other (like a clock made out of XNORs) can pulse each other either once per two ticks, or once per tick (both gates flipflop off and on during the same tick.)

How do I build one (with pipes?)

1. Ensure nothing has already been built or unanchored. Otherwise, you might fail.
2. Start with a pump of some kind - for example, the O2 chamber outlet pump. Locate its outlet.
3. Build a gas filter facing toward the pump's outlet.
4. Build a gas filter facing away from the pump's outlet, and join the three devices together in a loop:
   
5. Set the pump to 4499.9 kPa.

You're done. If you did it correctly, gas will start piling up beyond the 4500 kPa limit of a pump, and beyond 9000 of a volume pump.

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Q/A

...Why 4499?

Because if it was 4500, it would clog. The filter that's facing the output would see that "ah, my output's already at pressure limit!" and stop immediately.

Why would it fail if someone built or removed something? Like, does it apply to literally anything?

No, of course not. The only thing we care about here is pumps, valves, filters, mixers, freezers, anything that could be considered an active grounded pipe device. So long as that's never touched, you're good.
Otherwise, place some pumps until you've "filled" the metaphorical device gap that was caused by unanchoring.

That schematic above is confusing. Are those all filters? Should they be inverted?

Yes, those are all "filters", but the bottom left arrow could be anything so long as it doesn't pump >4500kPa.

Do we have to use filters?

Pretty much yes. Because filters are 5x stronger than volume pumps, and because a volume pump's maximum pumping volume per "tick" is 800L, which is a paltry 4 pipes of volume.
You can't make a GoidaTEG out of that if you tried.

How do I make tritium out of this?

Short story is you do steps 2 and 3 but with any of the last filters' side outputs. But for debugging, see the full length guide.

This doesn't read like a TL;DR at all. Why is there STILL an entire two screens of information?

Okay, look. You presumably asked how to build a subframe. You never asked to learn WHY is subframe. This is the smallest I could get with a high enough "replication success rate".

-router, 2025