The tested joint

Where cubes meet,
nothing gets in.

A modular bunker is only as tight as its joints. Here is how a CUBE Bunker joint is built and the tests every one of them has to pass, in the plant and on your site.

See the cubes

How it seals

Two gaskets,
bolted and welded.

The mate collar is a 1/2 in steel frame that bolts to the portal frames of both cubes with 88 galvanized cap screws, through two rings of EPDM gasket with a butyl bead. The gap between the cube walls outside the collar is closed with steel strips welded to both cubes and coated. Utility ports sit inside the gasket line, so water, power and air pass through without a hole to the soil.

CUBE A interior (bath)CUBE B interior (hall / plumbing)42 in PORTALclear walkway, nothing in itmate collar + gasketLOW PORTHIGH PORTLow port: water supply, pumped gray water, power. High port: exhaust duct, data.Both sit in the portal frame inside the collar gasket; jumpers snap together on site.

The tests

Five tests.
Every joint.

Each one is recorded, signed and kept with your project. We publish results from production builds here as they are completed.

  1. Every seam, in the plantVacuum box test on every weld of every cube to ASME Section V Article 10 practice, then the whole cube air tested at 1.5 psig and held 30 minutes with no measurable drop.
  2. The collar, in the plantEach mate collar is fit-checked against a master portal frame, and its two EPDM gasket rings are checked for compression at the specified cap-screw torque.
  3. The joint, on siteAll cap screws torqued in a star pattern and marked; closure strips seal-welded, vacuum-box tested and coated; coating spark tested over every field weld.
  4. The whole bunker, on siteBefore backfill, the sealed bunker is held at 0.5 psig for 30 minutes. Any loss is found with soap solution and fixed, and the test is repeated until it holds.
  5. After backfillPositive-pressure check with the air system running and a smoke test at every joint from inside. Results go in your handover binder.