However Spain, with a dominant scrum, had other ideas and took the game to Wales on the 3G pitch in the second spell. No 8 Ana Mari Aigneren proved a constant threat from the back of the scrum but the visitors were unable to turn her charging runs into points on the board.
Wales head coach Rhys Edwards took the opportunity to blood new players at this level with props Megan York and Bethan Howell along with winger Rafique Taylor given the chance to nail down a Six Nations squad berth.
All three will be hoping they did enough to earn selection for Wales' opening Six Nations clash against Ireland in Aberavon on February 3rd, after acquitting themselves well.
Flanker Catrina Nicholas, returning to international level after missing last year's Six Nations through unavailability, led the defensive effort superbly for Wales as Spain turned up the heat in the second half. Back row colleagues Sioned Harries and Vicky Owens followed her lead while Rebecca de Filippo marshalled the backs well and also carved open a few holes in the Spanish defence with her strength in attack.
Edwards was delighted to get the win. "We don't normally get the opportunity to play this sort of game at this time of the year. The fact that we were up 7-0 at halftime was a huge boost for us," he said.
"We didn't have much ball in the second half but the defensive patterns were excellent. The last 15 minutes we were under extreme pressure so to get a win is obviously going to boost confidence as we head towards the Six Nations."
Wales captain Gemma Hallett, added: "Our defence won us the game in the end. They threw everything at us but we were able to hold them out. Our lineouts were pretty good as well but there are one or two things we need to work on like the scrum. But we will re-group and go into the first game of the Six Nations against Ireland with plenty of confidence."
Wales scorers: Try - Elen Evans; Con: Elinor Snowsill