They will have a fortnight of fitness work before the first pre-season game, at Grimsby on Thursday July 14.
After the annual game at Unibond side Brigg Town, the Iron will spend a week at a training camp in the Republic of Ireland.
They will play two League of Ireland sides while on the Emerald Isle, against Limerick on Monday 18 and Cobh Ramblers on Wednesday 20.
As the Irish domestic season runs through the summer, in an attempt to keep fans at games rather than in front of TVs watching Premiership action, both games will provide a tough test for United.
The two Irish sides appear evenly matched, and are among the Eircom First Division promotion challengers with 25 points apiece from their opening 15 games.
United will complete their pre-season without a glamourous game against 'big' opposition, as boss Brian Laws looks to work on fitness.
The only League side that the Iron will meet are League Two title favourites Northampton Town.
Laws said: "These fixtures may seem less attractive to fans, but it will be beneficial to the team and our preparation for the tough challenges ahead.
"It is vital that we have competitive, realistic and winnable games to gain confidence and momentum to hit the ground running for a good start to the new season."
United begin their League One campaign with a trip to Brentford on Saturday August 6.