Very cool picture, Grim. I'd agree that the cinder blocks look a little wonky. I think they're too sparkly -- too much highlight in the shader. As for the pipes, I think the shader on the cross pipes in the back is a little stretched along the length of the pipe. Maybe you need to repeat it more in one axis or the other.... Compositionally, I'd move the BG pipes down a bit so their lines lead your eye to the valve. The spiderweb might be a bit more subtle, for my tastes. Great modelling; I love the welding seam along the valve joint.