It’s a little larger than the Galveston Bay explosion.
According to Wikipedia the Texas City disaster had just over 2000 tonnes of ammonium nitrate explode (as opposed to 2700 in Beirut) which they claim to be “one of history's largest non-nuclear explosions”.
Was there some other factor that caused the Texas City to have a bigger blast?
If I'm reading it right, the Texas City disaster had 2300 tons on the Grandcamp, and 961 tons on a nearby ship, the High Flyer. That second ship exploded later in the day. There was also a chemical plant that was caught in the blast and a warehouse with fertilizer.