22 Grades Compared

Where a tanker can be discharged straight into the feed line and consumed within days, choose the lowest bands. A narrow window is not a weakness in this setting: it is what keeps the feed fresh, provided the schedule is reliable and the arrival test happens at the gate rather than the following day.

Mid-low bands cover the ordinary case: a delivery every week or two, a tank that is neither empty nor full, and a plant that runs a stable recipe. These grades tolerate a missed schedule without forcing an emergency purchase, which is the realistic test of a regional supply arrangement.

Once a container crosses an ocean, the yard and the vessel become part of the storage period. Mid bands are the practical choice for a voyage of three to five weeks into a temperate port, and they leave enough margin for customs delays without asking the receiving plant to handle a very short window.

Equatorial crossings and open-yard storage at destination both add heat, and heat is what spends the working window. Higher bands are specified for routes where the journey cannot be shortened and the port cannot guarantee covered storage, and the arrival test should happen before the container leaves the quay area.

Where material is bought ahead for a quarterly production plan, the band has to support a storage period rather than a journey. Choose a high band and pair it with a written rotation and re-test rule; without the rule, the extra margin is used up silently and the first sign of trouble is a batch that behaves unexpectedly.

Rail cars, barges and transhipment points add handovers, and every handover adds time that nobody schedules. The highest band exists for cargo that will be in motion or in a yard for months, and it should be paired with sealed openings, recorded seal numbers and an analysis at both loading and discharge.

A second source is only useful if the plant can absorb it without rewriting its storage instruction. Wide bands allow two routes or two suppliers to feed one tank, provided the arrival tolerance is agreed in writing and the first blended batch is run as a qualification batch against the reference curve.

Copolymer plants should select on logistics radius first and band second. A line charging within days belongs on a low band, a sea-fed plant on a mid or high band, and either way the feed specification should include purity and water because copolymer composition responds to more than the inhibitor figure.

Where a customer claim needs supporting, the ECO-B grades carry the same specification and a mass balance attribution behind the lot. Choose the band by the same logistics logic as the conventional grades, then add the document discipline: attribution records filed against lot numbers, and a ledger reconciled before any statement is issued.