Alloys such as Argelite 71 / 61 would work fine for long span bridges.
things to keep in mind are: what type of porcelain will be used and also what type of porcelain application will be used (press or hand-stack). If you can share this info with me, I will be happy to further assist you!
We use Argelite 71 for 90% of our metal ceramics. We use it for singel, all the way to a roundhouse. Its a strong alloy that holds margins well. We use Vita porc as well.
Cloe, We have such a wide variety of alloy semi precious alloys as you can see by the responses on this thread. As mentioned... Argelite 71 is a great choice. as well as Argebond 80. I recommend and sell these two alloys all day long for use with VM-13. They both have minimal silver (5-10%) and the CTE is right where you need it. These two are also great for pressing. I would say Argelite 61 is not my ideal choice. Will definitley require slow cooling. I can give you more information about these and other possible choices. Contact me or your local Argen rep for more information.