Buccaneers' own Daniel Qualter will link up with Iain Henderson in the second row, while fellow Connacht native Aaron Conneely is named in the back row.
Centre JJ Hanarahan makes a return to the side from last year along with Sam Coghlan Murray who has been named on the left wing.
Kieran Marmion will take up the scrum half position and will partner Paddy Jackson who has been named at out-half. The Ulster-capped Jackson will also captain this year's side.
Speaking ahead of the opening game, Ruddock said: "We are all looking forward to the start of the Six Nations. It is always a tough test against Wales but preparations have been first class.
"We are confident we have prepared as best as we can and are now looking forward to transferring that training onto the pitch itself."
Friday's clash will be broadcast live on RTÉ Two, with commentary provided by Ryle Nugent and Donal Lenihan. It will also be shown on RTE.ie (Island of Ireland only).
IRELAND UNDER-20 Team & Replacements (v Wales Under-20s, RBS Under-20 6 Nations Championship, Dubarry Park, Buccaneers RFC, Friday, February 3, kick-off 7.05pm):
15 - Shane Layden (Buccaneers/Connacht)
14 - Barry Daly (UCD/Leinster)
13 - Foster Horan (Lansdowne/Leinster)
12 - JJ Hanrahan (UL Bohemians/Munster)
11 - Sam Coghlan Murray (UCD/Leinster)
9 - Kieran Marmion (Corinthians/Connacht)
1 - Kyle McCall (Ballynahinch/Ulster)
2 - Niall Scannell (Dolphin/Munster)
3 - Peter Reilly (Lansdowne/Leinster)
4 - Iain Henderson (Queen's University/Ulster)
5 - Daniel Qualter (Buccaneers/Connacht)
6 - Conor Gilsenan (UCD/Leinster)
7 - Aaron Conneely (Corinthians/Connacht)
8 - Jack Conan (Old Belvedere/Leinster)
16 - Des Merrey (Clontarf/Leinster)
17 - James Rael (Garryowen/Munster)
18 - Jake Cawley (Old Belvedere/Leinster)
19 - Tadhg Beirne (Lansdowne/Leinster)
20 - Jordan Coghlan (UCD/Leinster)
21 - Luke McGrath (UCD/Leinster)
22 - Cathal Marsh (Dublin University/Leinster)
23 - Christopher Farrell (Dungannon/Ulster)