The Iron drew their first game of pre-season in front of a record crowd at the Hawthorns.
United were 2-0 up through goals from Cameron Wilson and Danny Elliott before the hosts hit back to equalise following goals frm James Nichols and Andy Taylor.
The game was ended early following a medical emergency in the crowd, shortly after the equaliser.
It was Brigg who were fastest out of the blocks, winning the game's first corner inside the opening minute. Scunthorpe cleared that opportunity, with Danny Whitehall heading away before he surged upfield and looked for a return pass from Wilson, but the ball was intercepted.
Wilson was dangerous again, stealing possession in the third minute before finding Kian Scales down the right, only for a defender to clear his cross with Danny Whitehall lurking at the back post.
Scales was involved again a couple of minutes later after Alfie Beestin pulled a cross back from the left. Scales picked up the cross, cut onto his left and saw his shot blocked by a defender.
Whitehall then went close in the sixth minute, sending a 20-yard effort narrowly wide of the post. Callum Roberts was close to latching onto the loose ball before Brigg got the ball clear.
Eight minutes in, Beestin was played in, seeing his shot parried towards the goal before the loose ball is cleared for a corner with Whitehall sliding in.
United nearly found themselves a goal down on 10 minutes when a low cross is delivered from the right, with a glancing touch seeing the ball go across goal and narrowly wide of Ross Fitzsimons' right-hand post.
The best chance of the game so far fell to Wilson a minute later when a low cross is dinked in towards goal from the right, with his header looping towards the far corner, only for the home goalkeeper to push the ball wide for a corner.
Wilson again saw an effort blocked on 14 minutes following combination play between Scales and Roberts. The cutback fell to Wilson but he was denied by a defender.
United could have had a penalty two minues later when Whitehall was left on the deck following an upper body collision, but the referee was unmoved.
Wilson would get his goal on 20 minutes to put the Iron 1-0 up when he picked up the ball before driving into space, beyong a handful of Brigg players before slotting the ball across goal and into the net, despite the best efforts of a Zebras player on the line.
Two minutes later and Scunthorpe were looking to double their advantage. Roberts was forced wide by the Brigg goalkeeper, ending the first chance, but Denton would attack down the left soon after, with Roberts' header saved.
On 29 minutes, Roberts curled a free-kick, won moments before by himself, towards goal, with the goalkeeper again making a fine save.
12 minutes before half-time, the Iron were presented with another opportunity to make it 2-0. Beestin was the provider, feeding Roberts who sent his left-footed effort narrowly wide.
A succession of corners would follow for United over the next five minutes, but the hosts stood firm throughout, although Roberts did nearly register another shot on target, only for his effort to hit the inside leg of a defender and spin away from goal.
United made 10 changes at the interval, with only Scales retaining his place for the second 45.
Jason Law was in on the action from the start, winning a couple of corners, before delivering them into the area. On 53 minutes, he was slipped in on goal, with his shot going across goal and wide of the target.
Elliott had his first opportunity of the game just a minute later as he found himself in space only for his lobbed effort to clear the crossbar as well as the goalkeeper.
Just before the hour mark, Elliott was denied again, as he broke the offside trap but saw his right-footed effort blocked after checking back inside.
Nat Wallace was denied by the goalkeeper on 67 minutes after Elliott stormed through down the left. His cross searched for Poulter, but the ball ran through to Wallace who saw his scuffed effort saved.
Two minutes later and the lead was doubled, with Elliott getting a deserved goal. Wallace took the assist as the Iron forward latched onto possession before rounding the goalkeeper and slotting into an unguarded net.
The hosts gave their warning signs on 73 minutes when a give-and-go created space on the right side of the area, with the clipped effort glancing off the crossbar.
Less than 60 seconds later and the deficit was halved with an effort slotting into the net by Nichols from outside the penalty area.
And on 78 minutes, Brigg hit the equaliser when Taylor lifted the ball over the onrushing Chapman, with the ball landing in the net.
Soon after, play was halted following a medical emergency in the crowd, with the officials and management of both sides agreeing to end the game early. The club's thoughts are with the individual, and we hope he makes a swift recovery.
IRON FIRST HALF: Fitzsimons, Scales, Boyce, Kouougun, Denton, Shrimpton, Roberts, Clunan, Beestin, Wilson, Whitehall.
IRON SECOND HALF: Chapman, Scales, Barrows, Evans, Kelly, Wallace, Robertson, Butterfield, Law, Poulter, Elliott.
UNUSED SUBSTITUTE: Young.