EE & others were replacing the top belt on the #2 belt press. Takeup assembly was secured with a 3/4 ton chain come-a-long, both air regulators were backed off so as not to apply pressure & a stand with a 2""x12"" steel pipe was holding the new belt. The air valve was opened & the takeup swung forward, broke the chain & the pipe struck the injured on left ear which required stitches.