You need to set your Thread.CurrentPrincipal
after login i.e.
var claims = new List<Claim>();
claims.Add(new Claim(ClaimTypes.Name, result.UserFirstName));
claims.Add(new Claim(ClaimTypes.Sid, result.UserID.ToString()));
var identity = new ClaimsIdentity(claims, DefaultAuthenticationTypes.ApplicationCookie);
var claimsPrincipal = new ClaimsPrincipal(identity);
// Set current principal
Thread.CurrentPrincipal = claimsPrincipal;
Then the following will retrieve the values.
//Get the current claims principal
var identity = (ClaimsPrincipal)Thread.CurrentPrincipal;
// Get the claims values
var name = identity.Claims.Where(c => c.Type == ClaimTypes.Name)
.Select(c => c.Value).SingleOrDefault();
var sid = identity.Claims.Where(c => c.Type == ClaimTypes.Sid)
.Select(c => c.Value).SingleOrDefault();